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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

HTML

            
              <link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet">
<link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">
<body>
    <nav class="app-bar">
        <button onclick="HamburgerButtonClick();" class="button bar-button hamburger-button">
            <span class="material-icons">menu</span>
        </button>
        <div class="bar-font title">Sudoku</div>
        <div id="moreoption-sec" class="more-option-div more-button">
            <button onclick="moreOptionButtonClick()" class="button bar-button">
                <span class="material-icons">more_vert</span>
            </button>
            <!-- it is important to put these styles in here because if I do not do that it will not work in javaScript-->
            <div  id="more-option-list" style="visibility: hidden;max-height: 10px;max-width: 40px;min-width: 40px;" class="more-option-list">
                <button onclick="hintButtonClick()" ripple-color="#003c8f" class="button nav-item vertical-adjust">Hint</button>
                <button onclick="restartButtonClick()" ripple-color="#003c8f" class="button nav-item vertical-adjust">Restart</button>
                <button onclick="SurrenderButtonClick()" ripple-color="tomato" class="button nav-item vertical-adjust">Surrender</button>
            </div>
        </div>

        <button id="pause-btn" onclick="pauseGameButtonClick()" class="button bar-button more-button">
            <span id="pause-icon" class="material-icons">pause</span>
            <span id="pause-text">Pause</span>
        </button>
        <button id="check-btn" onclick="checkButtonClick()" class="button bar-button more-button">
            <span class="material-icons">done_all</span>
            <span>Check</span>
        </button>
        <button id="isunique-btn" style="display: none;" onclick="isUniqueButtonClick();" class="button bar-button more-button">
            <span class="material-icons">call_split</span>
            <span>Is unique</span>
        </button>
        <button id="solve-btn" style="display: none;" onclick="solveButtonClick()" class="button bar-button more-button">
            <span class="material-icons">border_color</span>
            <span>Solve</span>
        </button>

    </nav>

    <div id="hamburger-menu" class="hamburger-menu">
        <nav id="nav-menu" class="nav-menu">
            <div class="nav-head">
                <div class="nav-head-img">
                    <img src="https://image.ibb.co/jmuOKn/icon.jpg" art="" />
                </div>
                <div class="nav-head-title">Sudoku</div>
            </div>
            <ul class="nav-items">
                <button onclick="showDialogClick('dialog');" ripple-color="#003c8f" class="button nav-item vertical-adjust" >
                    <div>
                        <span class="material-icons">add</span>
                        <span style="left:12px;">New game</span>
                    </div>
                </button>
                <button onclick="sudokuSolverMenuClick();" ripple-color="#003c8f" class="button nav-item vertical-adjust" >
                    <div>
                        <span class="material-icons">edit</span>
                        <span style="left:12px;">Sudoku Solver</span>
                    </div>
                </button>
                <button onclick="showDialogClick('about-dialog');" ripple-color="#003c8f" class="button nav-item vertical-adjust" >
                    <div>
                        <span class="material-icons">star</span>
                        <span style="left:12px;">About</span>
                    </div>
                </button>
                <div class="bar-footer">
                    <ul>
                        <a href="#" class="bar-footer-link">Site feedback</a>
                        <a href="#" class="bar-footer-link">Privacy</a>
                        <a href="#" class="bar-footer-link">Terms</a>
                    </ul>
                </div>
            </ul>
        </nav>
        <div class="nav-menu-blank" onclick="hideHamburgerClick()">

        </div>
    </div>

    <div class="floating">
        <button onclick="showDialogClick('dialog');" class="button floating-btn vertical-adjust">
            <span class="material-icons">add</span>
        </button>
    </div>

    <div id="dialog" class="dialog">
        <div id="dialog-box" class="dialog-content">
            <div class="dialog-header">New game</div>

            <div class="dialog-body">
                <p>Select game difficulty to get started.</p>
                <ul>
                    <li class="radio-option">
                        <label for="very-easy">
                            <input id="very-easy" value="very easy" type="radio" name="difficulty"> Very easy
                        </label>
                    </li>
                    <li class="radio-option">
                        <label for="easy">
                            <input id="easy" value="easy" type="radio" name="difficulty"> Easy
                        </label>
                    </li>
                    <li class="radio-option">
                        <label for="normal">
                            <input id="normal" value="normal" type="radio" name="difficulty"> Normal
                        </label>
                    </li>
                    <li class="radio-option">
                        <label for="hard">
                            <input id="hard" value="hard" type="radio" name="difficulty"> Hard
                        </label>
                    </li>
                    <li class="radio-option">
                        <label for="very-hard">
                            <input id="very-hard" value="expert" type="radio" name="difficulty"> Expert
                        </label>
                    </li>
                </ul>
            </div>

            <div class="dialog-footer">
                <button onclick="startGameButtonClick();" ripple-color="#003c8f" class="button dialog-btn vertical-adjust" >OK</button>
                <button onclick="hideDialogButtonClick('dialog');" ripple-color="#202020" class="button dialog-btn vertical-adjust" >Cancel</button>
            </div>
        </div>
    </div>

    <div id="about-dialog" class="dialog">

        <div id="about-dialog-box" onblur="hideDialogButtonClick('about-dialog');" class="dialog-content about-dialog-content">
            <div class="dialog-header">CodeTeam6</div>

            <div class="dialog-body">
                <p>about us</p>
                <div class="card-group">
                    <div class="card dialog-card">
                        <div class="about-card-img">
                            <img src="https://image.ibb.co/crYHen/a_abdallah.jpg" alt="" />
                        </div>
                        <div class="about-card-title">Ahmad Abdalla</div>
                        <div class="about-card-content">Egypt</div>
                        <div class="about-card-quote">My dream is to be the best developer in the world, and I'll work continuously to achieve that.</div>
                    </div>
                    <div class="card dialog-card">
                        <div class="about-card-img">
                            <img src="https://image.ibb.co/mKg3Kn/a_alrifai.jpg" alt="" />
                        </div>
                        <div class="about-card-title">Ayman Alrifai</div>
                        <div class="about-card-content">Libya</div>
                        <div class="about-card-quote">I love coding & design. I learn every day to build awesome stuff.</div>
                    </div>
                    <div class="card dialog-card">
                        <div class="about-card-img">
                            <img src="https://image.ibb.co/dYd5X7/m_diab.jpg" alt="" />
                        </div>
                        <div class="about-card-title">Mohammad Diab</div>
                        <div class="about-card-content">Syria</div>
                        <div class="about-card-quote">Silent but deadly.</div>
                    </div>
                    <div class="card dialog-card">
                        <div class="about-card-img">
                            <img src="https://image.ibb.co/g01g5S/r_bhere.jpg" alt="" />
                        </div>
                        <div class="about-card-title">Reham Bhere</div>
                        <div class="about-card-content">Palestine</div>
                        <div class="about-card-quote">I think outside the box, I love trying everything new.</div>
                    </div>


                </div>
            </div>

            <div class="dialog-footer">
                <button onclick="hideDialogButtonClick('about-dialog');" ripple-color="#003c8f" class="button dialog-btn vertical-adjust"
                    >OK</button>
            </div>
        </div>
    </div>

    <div class="body" id="sudoku">
        <div class="card game">
            <table id="puzzle-grid">
                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

                <tr>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>

                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                    <td>
                        <input type="text" maxlength="1" onchange="checkInput(this)" disabled/>
                    </td>
                </tr>

            </table>
        </div>

        <div class="card status">
            <div id="game-number">game #0</div>
            <ul class="game-status">
                <li>
                    <div class="vertical-adjust">
                        <span class="material-icons">timer</span>
                        <span id="timer-label">Time</span>
                    </div>
                    <div id="timer" class="timer">00:00</div>
                </li>

                <li>
                    <div class="vertical-adjust">
                        <span class="material-icons">network_check</span>
                        <span id="game-difficulty-label">Game difficulty</span>
                    </div>
                    <div id="game-difficulty" class="timer">undefined</div>
                </li>
                <li>
                    <div class="vertical-adjust">
                        <span class="material-icons">grid_on</span>
                        <span>Remaining numbers</span>
                    </div>
                    <div class="remain-table">
                        <div class="remain-column">
                            <div class="remain-cell">
                                <div class="remain-cell-header">1</div>
                                <div onchange="document.write('Hello');" id="remain-1" class="remain-cell-content">0</div>
                            </div>
                            <div class="remain-cell">
                                <div class="remain-cell-header">4</div>
                                <div id="remain-4" class="remain-cell-content">0</div>
                            </div>
                            <div class="remain-cell">
                                <div class="remain-cell-header">7</div>
                                <div id="remain-7" class="remain-cell-content">0</div>
                            </div>
                        </div>
                        <div class="remain-column">
                            <div class="remain-cell">
                                <div class="remain-cell-header">2</div>
                                <div id="remain-2" class="remain-cell-content">0</div>
                            </div>
                            <div class="remain-cell">
                                <div class="remain-cell-header">5</div>
                                <div id="remain-5" class="remain-cell-content">0</div>
                            </div>
                            <div class="remain-cell">
                                <div class="remain-cell-header">8</div>
                                <div id="remain-8" class="remain-cell-content">0</div>
                            </div>
                        </div>
                        <div class="remain-column">
                            <div class="remain-cell">
                                <div class="remain-cell-header">3</div>
                                <div id="remain-3" class="remain-cell-content">0</div>
                            </div>
                            <div class="remain-cell">
                                <div class="remain-cell-header">6</div>
                                <div id="remain-6" class="remain-cell-content">0</div>
                            </div>
                            <div class="remain-cell">
                                <div class="remain-cell-header">9</div>
                                <div id="remain-9" class="remain-cell-content">0</div>
                            </div>
                        </div>

                    </div>
                </li>
            </ul>


            <!--<button class="option-button">
                    <span class="material-icons">pause</span>
                    <span>Pause</span>
                </button>
                <button class="option-button">
                    <span class="material-icons">done_all</span>
                    <span>Check</span>
                </button>
                <button class="option-button">
                    <span class="material-icons">help</span>
                    <span>Hint</span>
                </button>
                <button class="option-button">
                    <span class="material-icons">refresh</span>
                    <span>Restart</span>
                </button>
                <button class="option-button">
                    <span class="material-icons">flag</span>
                    <span>Surrender</span>
                </button>
            -->
        </div>
    </div>

    <div class="footer vertical-adjust">
        <span class="material-icons">code</span>
        <span>with</span>
        <span class="material-icons">favorite</span>
        <span>by Mohammad Diab from</span>
        <a href="#" onclick="showDialogClick('about-dialog');" >#codeTeam6</a>
        <span> . © 2018 all right reserved.</span>
    </div>
</body>
            
          
!

CSS

            
              * {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: Roboto, sans-serif;
}

html, body {
    background-color: rgb(235, 235, 240);
}

table {
    border: 2px solid #000000;
    border-spacing: 0;
    border-collapse: collapse;
    transition: all 0.5s;
}

ul {
    list-style-type: none;
}

td {
    border: 1px solid #000000;
    text-align: center;
    vertical-align: middle;
}

td input {
    color: #000000;
    padding: 0;
    border: 0;
    text-align: center;
    width: 48px;
    height: 48px;
    font-size: 24px;
    background-color: #FFFFFF;
    outline: none;
    text-transform: uppercase;
    transition: all 0.5s;
}

input:disabled {
    background-color: #bbdefb;
}

tr:nth-child(3n) {
    border-bottom: 4px solid #000000;
}

tr:nth-child(3n+1) {
    border-top: 4px solid #000000;
}

td:nth-child(3n) {
    border-right: 4px solid #000000;
}

td:nth-child(3n+1) {
    border-left: 4px solid #000000;
}

.right-cell {
    box-shadow: inset 0px 0px 20px 3px forestgreen;
}

.wrong-cell {
    box-shadow: inset 0px 0px 20px 3px tomato
}

.worning-cell {
    box-shadow: inset 0px 0px 20px 3px goldenrod;
}

/*Material Design*/

.app-bar {
    background: #49599a;
    width: 100%;
    position: fixed;
    height: 64px;
    color: #fff;
    box-shadow: 0 2px 4px 0 rgba(0, 0, 0, .14);
    z-index: 5;
    top: 0;
}

.bar-button {
    position: relative;
    background: transparent;
    border: none;
    outline: none;
    color: #fff;
    vertical-align: middle;
    padding: 0 22px;
    transition: all 0.5s;
}

.bar-button span {
    line-height: 64px;
    display: inline-block;
    vertical-align: middle;
}

.hamburger-button {
    float: left;
    left: 4px;
}

.bar-font {
    font-size: 18px;
    line-height: 64px;
}

.title {
    position: relative;
    float: left;
    left: 18px;
}

.more-button {
    float: right;
    /*right: 18px;*/
}

.hamburger-menu {
    background: rgba(0, 0, 0, 0.4);
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    z-index: 25;
    width: 100vw;
    height: 100vh;
    display: none;
    opacity: 0;
    transition: 0.1s all;
}

.nav-menu {
    border-right: 1px solid rgba(0, 0, 0, .4);
    background: #fff;
    color: #212121;
    position: fixed;
    left: -256px;
    top: 0;
    bottom: 0;
    width: 256px;
    z-index: 26;
    font-size: 15px;
    box-shadow: 16px 0 24px 2px rgba(0, 0, 0, .14);
    transition: all 0.3s;
}

.nav-menu-blank {
    position: relative;
    left: 256px;
    width: 100%;
    height: 100%;
}

.nav-head {
    height: 172px;
    background: #5e92f3;
    position: relative;
}

.nav-head-img {
    position: relative;
    border: 2px solid rgba(255, 255, 255, .4);
    border-radius: 50%;
    width: 96px;
    height: 96px;
    top: 16px;
    left: 16px;
    overflow: hidden;
}

.nav-head-img img {
    width: 100%;
    height: 100%;
}

.nav-head-title {
    color: #fff;
    position: absolute;
    bottom: 10px;
    margin-left: auto;
    margin-right: auto;
    left: 0px;
    right: 0;
    font-size: 22px;
    display: block;
    text-align: center;
}

.nav-items {
    margin-top: 12px;
}

.nav-item {
    font-weight: 700;
    display: block;
    color: #333;
    background: #0000;
    padding: 15px 0 15px 22px;
    letter-spacing: 1.1px;
    outline: none;
    border: none;
    width: 100%;
    text-align: left;
    margin: 0 !important;
}

.bar-footer {
    position: fixed;
    bottom: 12px;
    left: 10px;
}

.bar-footer-link {
    font-size: 12px;
    display: inline-block;
    margin: 0 8px;
    text-decoration: none;
    color: gray;
}

.body {
    width: 95%;
    max-width: 800px;
    margin: 96px auto 16px auto;
    display: flex;
}

.card {
    background: #fff;
    width: fit-content;
    box-shadow: 0 0 4px 0 rgba(0, 0, 0, .14);
    float: left;
    padding: 32px 32px 16px 32px;
}

.status {
    margin-left: 32px;
    padding-top: 10px;
    padding-left: 10px;
}

#game-number {
    font-size: 12px;
    color: gray;
}

.game-status {
    /*display: flex;
    flex-direction: column;
    justify-content: center;
    flex-flow: column;*/
    margin: 0 0 0 22px;
    height: 100%;
}

.game-status li {
    margin: 18px 0 0 0;
}

.vertical-adjust {
    margin: 12px 0;
}

.vertical-adjust span, .footer a {
    line-height: 24px;
    display: inline-block;
    vertical-align: middle;
}

.option-button {
    display: block;
    margin: 16px 8px 16px 30px;
    width: 130px;
    padding: 8px 10px;
    font-size: 16px;
    border: none;
    outline: none;
    box-shadow: 0 6px 10px 1px rgba(0, 0, 0, .14);
    border-radius: 2px;
    transition: all 0.5s;
    text-align: left;
}

.button {
    position: relative;
    overflow: hidden;
    cursor: pointer;
}

.option-button:hover {
    background: #1565c0;
}

.option-button:active {
    background: #3d7df4;
    box-shadow: 0 2px 4px 0 rgba(0, 0, 0, .24);
}

.option-button span {
    vertical-align: middle;
    line-height: 24px;
}

.ripple {
    position: absolute;
    background: #fff;
    border-radius: 50%;
    width: 5px;
    height: 5px;
    animation: ripple-effect 1.1s 1 cubic-bezier(.42, 0, .58, 1);
    opacity: 0;
}

@keyframes ripple-effect {
    0% {
        transform: scale(1);
        opacity: 0.4;
    }
    100% {
        transform: scale(100);
        opacity: 0;
    }
}

.timer {
    color: #1565c0;
    font-size: 32px;
    padding: 4px;
    box-shadow: 0 0 4px 0 rgba(0, 0, 0, .14);
    text-align: center;
}

.remain-table {
    position: relative;
    left: 0;
    right: 0;
    display: inline-block;
    margin: auto;
}

.remain-column {
    float: left;
    max-width: 64px;
}

.remain-cell {
    margin: 10px;
    text-align: center;
    border: solid 1px rgba(0, 0, 0, 0.2);
    ;
    box-shadow: 0 0 4px 0 rgba(0, 0, 0, .14);
}

.remain-cell div {
    padding: 5px 12px;
}

.remain-cell-header {
    background-color: #1565c0;
    color: white;
    font-weight: bold;
    border-bottom: solid 2px rgba(0, 0, 0, 0.2);
}

.red {
    background: #ff6659;
    color: #9a0007;
}

.gray {
    background: #808080;
    color: #404040;
}

.floating {
    position: fixed;
    bottom: 64px;
    right: 64px;
    z-index: 20;
}

.floating-btn {
    position: fixed;
    bottom: 48px;
    right: 48px;
    border-radius: 50%;
    padding: 12px;
    border: none;
    background-color: #1565c0;
    color: #fff;
    box-shadow: 0 6px 10px 0 rgba(0, 0, 0, .14);
    outline: none;
    z-index: 21;
}

.dialog {
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.4);
    z-index: 50;
    display: none;
    transition: all 0.2s;
}

.dialog-content {
    top: -200px;
    background: #fff;
    width: 90%;
    max-width: 540px;
    height: fit-content;
    margin: auto;
    vertical-align: middle;
    box-shadow: 0 24px 38px 3px rgba(0, 0, 0, 0.14);
    z-index: 51;
    transition: all 0.5s;
}

.dialog-header {
    font-size: 24px;
    font-weight: bold;
    padding: 16px 32px;
    border-bottom: solid 1px #808080;
}

.dialog-body p {
    margin: 16px 0 4px 28px;
    color: gray;
}

.radio-option {
    padding: 0 36px;
    list-style-type: none;
    position: relative;
}

.radio-option input {
    outline: none;
    margin-right: 12px
}

.radio-option label {
    display: block;
    height: 24px;
    cursor: pointer;
    padding: 1.25em 0;
}

.dialog-footer {
    border-top: solid 1px #808080;
    margin-top: 24px;
    text-align: right;
    padding-right: 16px;
}

.dialog-btn {
    background: transparent;
    border: none;
    color: #003c8f;
    font-size: 16px;
    margin: 8px 0;
    padding: 8px 16px;
    outline: none;
    min-width: 96px;
    display: inline-block;
}

.footer {
    text-align: center;
    color: white;
    background-color: #49599a;
    margin: 44px 0 0 0;
    padding: 8px;
}

.footer a {
    color: white;
}

.about-dialog-content {
    max-width: 720px;
}

.card-group {
    overflow: hidden;
    width: fit-content;
    margin: 0 auto;
    padding: 16px 0;
    display: flex;
}

.dialog-card {
    padding: 16px;
    margin: 8px;
    max-width: 160px;
}

.about-card-quote {
    color: #606060;
    font-size: 14px;
    margin-top: 16px;
}

.about-card-img {
    margin: 16px auto;
    overflow: hidden;
    border-radius: 50%;
    box-shadow: 0 0 4px 0 rgba(0, 0, 0, .14);
    width: fit-content;
}

.about-card-img img {
    width: 96px;
    height: auto;
}

.about-card-title {
    font-size: 16px;
    margin: 8px 0;
}

.about-card-content {
    font-size: 15px;
    margin: 4px 0;
}

.more-option-div {
    position: static;
    display: inline-block;
    margin-right: 16px;
}

.more-option-list {
    display: block;
    position: absolute;
    background-color: #fff;
    overflow: hidden;
    box-shadow: 0px 8px 10px 1px rgba(0, 0, 0, 0.14);
    right: 18px;
    z-index: 25;
    transition: all 0.2s cubic-bezier(0.4, 0.0, 0.6, 1);
}
            
          
!

JS

            
              // grid variable
var table;

// game number
var gameId = 0;

// puzzle grid
var puzzle = [];

// solution grid 
var solution = [];

// remaining number counts
var remaining = [9, 9, 9, 9, 9, 9, 9, 9, 9];

// variable to check if "Sudoku Solver" solve the puzzle
var isSolved = false;
var canSolved = true;

// stopwatch timer variables
var timer = 0;
var pauseTimer = false;
var intervalId;
var gameOn = false;

function newGame(difficulty) {

    // get random position for numbers from '1' to '9' to generate a random puzzle
    var grid = getGridInit();

    // prepare rows, columns and blocks to solove the initioaled grid
    var rows = grid;
    var cols = getColumns(grid);
    var blks = getBlocks(grid);

    //          solve the grid section
    // generate allowed digits for each cell
    var psNum = generatePossibleNumber(rows, cols, blks);

    // solve the grid
    solution = solveGrid(psNum, rows, true);

    // reset the game state timer and remaining number
    timer = 0;
    for (var i in remaining)
        remaining[i] = 9;

    // empty cells from grid depend on difficulty
    // for now it will be:
    // 59 empty cells for very easy
    // 64 empty cells for easy
    // 69 empty cells for normal
    // 74 empty cells for hard
    // 79 empty cells for expert
    puzzle = makeItPuzzle(solution, difficulty);

    // game is on when the difficulty = [0, 4]
    gameOn = difficulty < 5 && difficulty >= 0;

    // update the UI
    ViewPuzzle(puzzle);
    updateRemainingTable();

    // finally, start the timer
    if (gameOn)
        startTimer();
}

function getGridInit() {
    var rand = [];
    // for each digits from 1 to 9 find a random row and column 
    for (var i = 1; i <= 9; i++) {
        var row = Math.floor(Math.random() * 9);
        var col = Math.floor(Math.random() * 9);
        var accept = true;
        for (var j = 0; j < rand.length; j++) {

            // if number exist or there is a number already located in then ignore and try again
            if (rand[j][0] == i | (rand[j][1] == row & rand[j][2] == col)) {
                accept = false;

                // try to get a new position for this number
                i--;
                break;
            }
        }
        if (accept) {
            rand.push([i, row, col]);
        }
    }

    // initialize new empty grid 
    var result = [];
    for (var i = 0; i < 9; i++) {
        var row = "000000000";
        result.push(row);
    }

    // put numbers in the grid
    for (var i = 0; i < rand.length; i++) {
        result[rand[i][1]] = replaceCharAt(result[rand[i][1]], rand[i][2], rand[i][0]);
    }

    return result;
}

// return columns from a row grid
function getColumns(grid) {
    var result = ["", "", "", "", "", "", "", "", ""];
    for (var i = 0; i < 9; i++) {
        for (var j = 0; j < 9; j++)
            result[j] += grid[i][j];
        /*try {
            result[j] += grid[i][j];
        } catch (err) {
            alert(grid);
        }*/

    }
    return result;
}

// return blocks from a row grid
function getBlocks(grid) {
    var result = ["", "", "", "", "", "", "", "", ""];
    for (var i = 0; i < 9; i++) {
        for (var j = 0; j < 9; j++)
            result[Math.floor(i / 3) * 3 + Math.floor(j / 3)] += grid[i][j];
    }
    return result;
}

// function to replace char in string
function replaceCharAt(string, index, char) {
    if (index > string.length - 1) return string;
    return string.substr(0, index) + char + string.substr(index + 1);
}

// get allowed numbers that can be placed in each cell
function generatePossibleNumber(rows, columns, blocks) {
    var psb = [];

    // for each cell get numbers that are not viewed in a row, column or block
    // if the cell is not empty then, allowed number is the number already exist in it
    for (var i = 0; i < 9; i++) {
        for (var j = 0; j < 9; j++) {
            psb[i * 9 + j] = "";
            if (rows[i][j] != 0) {
                psb[i * 9 + j] += rows[i][j];
            } else {
                for (var k = '1'; k <= '9'; k++) {
                    if (!rows[i].includes(k))
                        if (!columns[j].includes(k))
                            if (!blocks[Math.floor(i / 3) * 3 + Math.floor(j / 3)].includes(k))
                                psb[i * 9 + j] += k;
                }
            }
        }
    }
    return psb;
}

function solveGrid(possibleNumber, rows, startFromZero) {
    var solution = [];

    // solve Sudoku with a backtracking algorithm
    // Steps are:
    //  1.  get all allowed numbers that fit in each empty cell
    //  2.  generate all possible rows that fit in the first row depend on the allowed number list
    //` 3.  select one row from possible row list and put it in the first row
    //  4.  go to next row and find all possible number that fit in each cell
    //  5.  generate all possible row fit in this row then go to step 3 until reach the last row or there aren't any possible rows left
    //  6.  if next row hasn't any possible left then go the previous row and try the next possibility from possibility rows' list
    //  7.  if the last row has reached and a row fit in it has found then the grid has solved

    var result = nextStep(0, possibleNumber, rows, solution, startFromZero);
    if (result == 1)
        return solution;
}

// level is current row number in the grid
function nextStep(level, possibleNumber, rows, solution, startFromZero) {
    // get possible number fit in each cell in this row
    var x = possibleNumber.slice(level * 9, (level + 1) * 9);

    // generate possible numbers sequence that fit in the current row
    var y = generatePossibleRows(x);
    if (y.length == 0)
        return 0;

    // to allow check is solution is unique
    var start = startFromZero ? 0 : y.length - 1;
    var stop = startFromZero ? y.length - 1 : 0;
    var step = startFromZero ? 1 : -1;
    var condition = startFromZero ? (start <= stop) : (start >= stop);

    // try every numbers sequence in this list and go to next row
    for (var num = start; condition; num += step) {
        var condition = startFromZero ? (num + step <= stop) : (num + step >= stop);
        for (var i = level + 1; i < 9; i++)
            solution[i] = rows[i];
        solution[level] = y[num];
        if (level < 8) {
            /*if (solution[4] === undefined) {
                var x = 0;
                x++;
            }*/
            var cols = getColumns(solution);
            var blocks = getBlocks(solution);

            var poss = generatePossibleNumber(solution, cols, blocks);
            if (nextStep(level + 1, poss, rows, solution, startFromZero) == 1)
                return 1;
        }
        if (level == 8)
            return 1;
    }
    return -1;
}

// generate possible numbers sequence that fit in the current row
function generatePossibleRows(possibleNumber) {
    var result = [];

    function step(level, PossibleRow) {
        if (level == 9) {
            result.push(PossibleRow);
            return;
        }

        for (var i in possibleNumber[level]) {
            if (PossibleRow.includes(possibleNumber[level][i]))
                continue;
            step(level + 1, PossibleRow + possibleNumber[level][i]);
        }
    }

    step(0, "");

    return result;
}

// empty cell from grid depends on the difficulty to make the puzzle
function makeItPuzzle(grid, difficulty) {
    /*
        difficulty:
        // expert   : 0;
        // hard     : 1;
        // Normal   : 2;
        // easy     : 3;
        // very easy: 4;
    */

    // empty_cell_count = 5 * difficulty + 20
    // when difficulty = 13, empty_cell_count = 85 > (81 total cells count)
    // so the puzzle is showen as solved grid
    if (!(difficulty < 5 && difficulty > -1))
        difficulty = 13;
    var remainedValues = 81;
    var puzzle = grid.slice(0);

    // function to remove value from a cell and its symmetry then return remained values
    function clearValue(grid, x, y, remainedValues) {
        function getSymmetry(x, y) {
            var symX = 8 - x;  //Symmetry
            var symY = 8 - y;
            return [symX, symY];
        }
        var sym = getSymmetry(x, y);
        if (grid[y][x] != 0) {
            grid[y] = replaceCharAt(grid[y], x, "0")
            remainedValues--;
            if (x != sym[0] && y != sym[1]) {
                grid[sym[1]] = replaceCharAt(grid[sym[1]], sym[0], "0")
                remainedValues--;
            }
        }
        return remainedValues;
    }

    // remove value from a cell and its symmetry to reach the expected empty cells amount
    while (remainedValues > (difficulty * 5 + 20)) {
        var x = Math.floor(Math.random() * 9);
        var y = Math.floor(Math.random() * 9);
        remainedValues = clearValue(puzzle, x, y, remainedValues);
    }
    return puzzle;
}

// view grid in html page
function ViewPuzzle(grid) {
    for (var i = 0; i < grid.length; i++) {
        for (var j = 0; j < grid[i].length; j++) {
            var input = table.rows[i].cells[j].getElementsByTagName('input')[0];
            addClassToCell(table.rows[i].cells[j].getElementsByTagName('input')[0]);
            if (grid[i][j] == "0") {
                input.disabled = false;
                input.value = "";
            }
            else {
                input.disabled = true;
                input.value = grid[i][j];
                remaining[grid[i][j] - 1]--;
            }
        }
    }
}

// read current grid
function readInput() {
    var result = [];
    for (var i = 0; i < 9; i++) {
        result.push("");
        for (var j = 0; j < 9; j++) {
            var input = table.rows[i].cells[j].getElementsByTagName('input')[0];
            if (input.value == "" || input.value.length > 1 || input.value == "0") {
                input.value = ""
                result[i] += "0";
            }
            else
                result[i] += input.value;
        }
    }
    return result;
}

// check value if it is correct or wrong
// return:
//  0 for value can't be changed
//  1 for correct value
//  2 for value that hasn't any conflict with other values
//  3 for value that conflict with value in its row, column or block
//  4 for incorect input
function checkValue(value, row, column, block, defaultValue, currectValue) {
    if (value === "" || value === '0')
        return 0;
    if (!(value > '0' && value < ':'))
        return 4;
    if (value === defaultValue)
        return 0;
    if ((row.indexOf(value) != row.lastIndexOf(value))
        || (column.indexOf(value) != column.lastIndexOf(value))
        || (block.indexOf(value) != block.lastIndexOf(value))) {
        return 3;
    }
    if (value !== currectValue)
        return 2;
    return 1;
}

// remove old class from input and add a new class to represent current cell's state
function addClassToCell(input, className) {
    // remove old class from input
    input.classList.remove("right-cell");
    input.classList.remove("worning-cell");
    input.classList.remove("wrong-cell");

    if (className != undefined)
        input.classList.add(className);
}

// update value of remaining numbers in html page
function updateRemainingTable() {
    for (var i = 1; i < 10; i++) {
        var item = document.getElementById("remain-" + i);
        item.innerText = remaining[i - 1];
        item.classList.remove("red");
        item.classList.remove("gray");
        if (remaining[i - 1] === 0)
            item.classList.add("gray");
        else if (remaining[i - 1] < 0 || remaining[i - 1] > 9)
            item.classList.add("red");
    }
}

// start stopwatch timer
function startTimer() {
    var timerDiv = document.getElementById("timer");
    clearInterval(intervalId);

    // update stopwatch value every one second
    pauseTimer = false;
    intervalId = setInterval(function () {
        if (!pauseTimer) {
            timer++;
            var min = Math.floor(timer / 60);
            var sec = timer % 60;
            timerDiv.innerText = (("" + min).length < 2 ? ("0" + min) : min) + ":" + (("" + sec).length < 2 ? ("0" + sec) : sec);
        }
    }, 1000);
}

// solve sudoku function
// input: changeUI boolean      true to allow function to change UI
// output:
//  0 when everything goes right
//  1 when grid is already solved
//  2 when Invalid input
//  3 when no solution
function solveSudoku(changeUI) {

    // read current state
    puzzle = readInput();

    var columns = getColumns(puzzle);
    var blocks = getBlocks(puzzle);

    // check if there is any conflict
    var errors = 0;
    var correct = 0;

    for (var i = 0; i < puzzle.length; i++) {
        for (var j = 0; j < puzzle[i].length; j++) {
            var result = checkValue(puzzle[i][j], puzzle[i], columns[j], blocks[Math.floor(i / 3) * 3 + Math.floor(j / 3)], -1, -1);
            correct = correct + ((result === 2) ? 1 : 0);
            errors = errors + ((result > 2) ? 1 : 0);
            addClassToCell(table.rows[i].cells[j].getElementsByTagName('input')[0], result > 2 ? "wrong-cell" : undefined)
        }
    }

    // check if invalid input
    if (errors > 0) {
        canSolved = false;
        return 2;
    }

    canSolved = true;
    isSolved = true;

    // check if grid is already solved
    if (correct === 81) {
        return 1;
    }


    //read the current time
    var time = Date.now();

    // solve the grid
    solution = solveGrid(generatePossibleNumber(puzzle, columns, blocks), puzzle, true);

    // show result
    // get time
    time = Date.now() - time;

    if (changeUI)
        document.getElementById("timer").innerText = Math.floor(time / 1000) + "." + ("000" + (time % 1000)).slice(-3);


    if (solution === undefined) {
        isSolved = false;
        canSolved = false;
        return 3;
    }

    if (changeUI) {
        remaining = [0, 0, 0, 0, 0, 0, 0, 0, 0];
        updateRemainingTable();
        ViewPuzzle(solution);
    }
    return 0;
}

// hide more option menu
function hideMoreOptionMenu() {
    var moreOptionList = document.getElementById("more-option-list");
    if (moreOptionList.style.visibility == "visible") {
        moreOptionList.style.maxWidth = "40px";
        moreOptionList.style.minWidth = "40px";
        moreOptionList.style.maxHeight = "10px";
        moreOptionList.style.opacity = "0";
        setTimeout(function () {
            moreOptionList.style.visibility = "hidden";
        }, 175);
    }
}


// UI Comunication functions

// function that must run when document loaded
window.onload = function () {

    // assigne table to its value
    table = document.getElementById("puzzle-grid");
    // add ripple effect to all buttons in layout
    var rippleButtons = document.getElementsByClassName("button");
    for (var i = 0; i < rippleButtons.length; i++) {
        rippleButtons[i].onmousedown = function (e) {
            // get ripple effect's position depend on mouse and button position
            var x = e.pageX - this.offsetLeft;
            var y = e.pageY - this.offsetTop;

            // add div that represents the ripple
            var rippleItem = document.createElement("div");
            rippleItem.classList.add('ripple');
            rippleItem.setAttribute("style", "left: " + x + "px; top: " + y + "px");

            // if ripple item should have special color... get and apply it 
            var rippleColor = this.getAttribute('ripple-color');
            if (rippleColor)
                rippleItem.style.background = rippleColor;
            this.appendChild(rippleItem);

            // set timer to remove the dif after the effect ends
            setTimeout(function () {
                rippleItem.parentElement.removeChild(rippleItem);
            }, 1500);
        };
    }
    for (var i = 0; i < 9; i++) {
        for (var j = 0; j < 9; j++) {
            var input = table.rows[i].cells[j].getElementsByTagName('input')[0];

            // add function to remove color from cells and update remaining numbers table when it get changed
            input.onchange = function () {

                //remove color from cell
                addClassToCell(this);

                // check if the new value entered is allowed
                function checkInput(input) {
                    if (input.value[0] < '1' || input.value[0] > '9') {
                        if (input.value != "?" && input.value != "؟") {
                            input.value = "";
                            alert("only numbers [1-9] and question mark '?' are allowed!!");
                            input.focus()
                        }
                    }
                }
                checkInput(this);

                // compare old value and new value then update remaining numbers table 
                if (this.value > 0 && this.value < 10)
                    remaining[this.value - 1]--;
                if (this.oldvalue !== "") {
                    if (this.oldvalue > 0 && this.oldvalue < 10)
                        remaining[this.oldvalue - 1]++;
                }

                //reset canSolved value when change any cell
                canSolved = true;

                updateRemainingTable();
            };

            //change cell 'old value' when it got focused to track numbers and changes on grid
            input.onfocus = function () {
                this.oldvalue = this.value;
            };
        }
    }
}

// function to hide dialog opened in window
window.onclick = function (event) {
    var d1 = document.getElementById("dialog");
    var d2 = document.getElementById("about-dialog");
    var m1 = document.getElementById("more-option-list");

    if (event.target == d1) {
        hideDialogButtonClick("dialog");
    } else if (event.target == d2) {
        hideDialogButtonClick("about-dialog");
    } else if (m1.style.visibility == "visible") {
        hideMoreOptionMenu();
    }
}

// show hamburger menu
function HamburgerButtonClick() {
    var div = document.getElementById("hamburger-menu");
    var menu = document.getElementById("nav-menu");
    div.style.display = "block";
    div.style.visibility = "visible";
    setTimeout(function () {
        div.style.opacity = 1;
        menu.style.left = 0;
    }, 50);
}

// start new game
function startGameButtonClick() {
    var difficulties = document.getElementsByName('difficulty');
    // difficulty:
    //  0 expert
    //  1 hard
    //  2 normal
    //  3 easy
    //  4 very easy
    //  5 solved

    // initial difficulty to 5 (solved)
    var difficulty = 5;

    // get difficulty value
    for (var i = 0; i < difficulties.length; i++) {
        if (difficulties[i].checked) {
            newGame(4 - i);
            difficulty = i;
            break;
        }
    }
    if (difficulty > 4)
        newGame(5);

    hideDialogButtonClick('dialog');
    gameId++;
    document.getElementById("game-number").innerText = "game #" + gameId;


    // hide solver buttons
    // show other buttons
    document.getElementById("moreoption-sec").style.display = "block";
    document.getElementById("pause-btn").style.display = "block";
    document.getElementById("check-btn").style.display = "block";
    document.getElementById("isunique-btn").style.display = "none";
    document.getElementById("solve-btn").style.display = "none";

    // prerpare view for new game
    document.getElementById("timer-label").innerText = "Time";
    document.getElementById("timer").innerText = "00:00";
    document.getElementById("game-difficulty-label").innerText = "Game difficulty";


    document.getElementById("game-difficulty").innerText = difficulty < difficulties.length ? difficulties[difficulty].value : "solved";
}

// pause \ continue button click function
function pauseGameButtonClick() {
    var icon = document.getElementById("pause-icon");
    var label = document.getElementById("pause-text");

    // change icon and label of the button and hide or show the grid
    if (pauseTimer) {
        icon.innerText = "pause";
        label.innerText = "Pause";
        table.style.opacity = 1;
    }
    else {
        icon.innerText = "play_arrow";
        label.innerText = "Continue";
        table.style.opacity = 0;
    }

    pauseTimer = !pauseTimer;
}

// check grid if correct
function checkButtonClick() {

    // check if game is started
    if (gameOn) {

        // add one minute to the stopwatch as a cost of grid's check
        timer += 60;
        var currentGrid = [];

        // read gritd status
        currentGrid = readInput();

        var columns = getColumns(currentGrid);
        var blocks = getBlocks(currentGrid);

        var errors = 0;
        var currects = 0;

        for (var i = 0; i < currentGrid.length; i++) {
            for (var j = 0; j < currentGrid[i].length; j++) {
                if (currentGrid[i][j] == "0")
                    continue;

                // check value if it is correct or wrong
                var result = checkValue(currentGrid[i][j], currentGrid[i], columns[j], blocks[Math.floor(i / 3) * 3 + Math.floor(j / 3)], puzzle[i][j], solution[i][j]);

                // remove old class from input and add a new class to represent current cell's state
                addClassToCell(table.rows[i].cells[j].getElementsByTagName('input')[0], result === 1 ? "right-cell" : (result === 2 ? "worning-cell" : (result === 3 ? "wrong-cell" : undefined)));

                if (result === 1 || result === 0) {
                    currects++;
                } else if (result === 3) {
                    errors++;
                }
            }
        }

        // if all values are correct and they equal original values then game over and the puzzle has been solved
        // if all values are correct and they aren't equal original values then game over but the puzzle has not been solved yet
        if (currects === 81) {
            gameOn = false;
            pauseTimer = true;
            document.getElementById("game-difficulty").innerText = "Solved";
            clearInterval(intervalId);
            alert("Congrats, You solved it.");
        } else if (errors === 0 && currects === 0) {
            alert("Congrats, You solved it, but this is not the solution that I want.");
        }
    }
}

// restart game
function restartButtonClick() {

    if (gameOn) {
        // reset remaining number table
        for (var i in remaining)
            remaining[i] = 9;

        // review puzzle
        ViewPuzzle(puzzle);

        // update remaining numbers table
        updateRemainingTable();

        // restart the timer
        // -1 is because it take 1 sec to update the timer so it will start from 0
        timer = -1;
    }
}

// surrender
function SurrenderButtonClick() {

    if (gameOn) {
        // reset remaining number table
        for (var i in remaining)
            remaining[i] = 9;

        // review puzzle
        ViewPuzzle(solution);

        // update remaining numbers table
        updateRemainingTable();

        // stop the game
        gameOn = false;
        pauseTimer = true;
        clearInterval(intervalId);

        // mark game as solved
        document.getElementById("game-difficulty").innerText = "Solved";
    }
}

// hint
function hintButtonClick() {
    if (gameOn) {

        // get list of empty cells and list of wrong cells
        var empty_cells_list = [];
        var wrong_cells_list = [];
        for (var i = 0; i < 9; i++) {
            for (var j = 0; j < 9; j++) {
                var input = table.rows[i].cells[j].getElementsByTagName('input')[0];
                if (input.value == "" || input.value.length > 1 || input.value == "0") {
                    empty_cells_list.push([i, j])
                }
                else {
                    if (input.value !== solution[i][j])
                        wrong_cells_list.push([i, j])
                }
            }
        }

        // check if gird is solved if so stop the game
        if (empty_cells_list.length === 0 && wrong_cells_list.length === 0) {
            gameOn = false;
            pauseTimer = true;
            document.getElementById("game-difficulty").innerText = "Solved";
            clearInterval(intervalId);
            alert("Congrats, You solved it.");
        } else {

            // add one minute to the stopwatch as a cost for given hint
            timer += 60;

            // get random cell from empty or wrong list and put the currect value in it
            var input
            if ((Math.random() < 0.5 && empty_cells_list.length > 0) || wrong_cells_list.length === 0) {
                var index = Math.floor(Math.random() * empty_cells_list.length)
                input = table.rows[empty_cells_list[index][0]].cells[empty_cells_list[index][1]].getElementsByTagName('input')[0];
                input.oldvalue = input.value;
                input.value = solution[empty_cells_list[index][0]][empty_cells_list[index][1]];
                remaining[input.value - 1]--;
            } else {
                var index = Math.floor(Math.random() * wrong_cells_list.length)
                input = table.rows[wrong_cells_list[index][0]].cells[wrong_cells_list[index][1]].getElementsByTagName('input')[0];
                input.oldvalue = input.value;
                remaining[input.value - 1]++;
                input.value = solution[wrong_cells_list[index][0]][wrong_cells_list[index][1]];
                remaining[input.value - 1]--;
            }

            // update remaining numbers table
            updateRemainingTable();
        }

        // make updated cell blinking
        var count = 0
        for (var i = 0; i < 6; i++) {
            setTimeout(function () {
                if (count % 2 == 0)
                    input.classList.add("right-cell");
                else
                    input.classList.remove("right-cell");
                count++;
            }, i * 750)
        }
    }
}

function showDialogClick(dialogId) {
    // to hide navigation bar if it opened
    hideHamburgerClick();

    var dialog = document.getElementById(dialogId);
    var dialogBox = document.getElementById(dialogId + "-box");
    dialogBox.focus();
    dialog.style.opacity = 0;
    dialogBox.style.marginTop = "-500px";
    dialog.style.display = "block";
    dialog.style.visibility = "visible";

    // to view and move the dialog to the correct position after it set visible
    setTimeout(function () {
        dialog.style.opacity = 1;
        dialogBox.style.marginTop = "64px";
    }, 200);
}

// show more option menu
function moreOptionButtonClick() {
    var moreOptionList = document.getElementById("more-option-list");

    // timeout to avoid hide menu immediately in window event
    setTimeout(function () {
        if (moreOptionList.style.visibility == "hidden") {
            moreOptionList.style.visibility = "visible";
            setTimeout(function () {
                moreOptionList.style.maxWidth = "160px";
                moreOptionList.style.minWidth = "160px";
                moreOptionList.style.maxHeight = "160px";
                moreOptionList.style.opacity = "1";
            }, 50);
        }
    }, 50);
}

function hideDialogButtonClick(dialogId) {
    var dialog = document.getElementById(dialogId);
    var dialogBox = document.getElementById(dialogId + "-box");
    dialog.style.opacity = 0;
    dialogBox.style.marginTop = "-500px";

    setTimeout(function () {
        dialog.style.visibility = "collapse";
        //dialog.style.display = "none";
    }, 500);
}

// hide hamburger menu when click outside
function hideHamburgerClick() {
    var div = document.getElementById("hamburger-menu");
    var menu = document.getElementById("nav-menu");
    menu.style.left = "-256px";

    setTimeout(function () {
        div.style.opacity = 0;
        //divstyle.display = "none";
        div.style.visibility = "collapse";
    }, 200);
}


// sudoku solver section

function sudokuSolverMenuClick() {

    // hide hamburger menu
    hideHamburgerClick();

    //stop current game if its running
    if (gameOn) {
        gameOn = false;
        clearInterval(intervalId);
    }


    solution = [];
    canSolved = true;
    isSolved = false;

    // generate empty grid
    var grid = [];
    for (var i = 0; i < 9; i++) {
        grid.push("");
        for (var j = 0; j < 9; j++) {
            grid[i] += "0";
        }
    }

    // view empty grid... allow user to edit all cells
    ViewPuzzle(grid);

    // update remaining table
    remaining = [9, 9, 9, 9, 9, 9, 9, 9, 9];
    updateRemainingTable();

    // show solve and check unique buttons
    // hide other buttons
    document.getElementById("moreoption-sec").style.display = "none";
    document.getElementById("pause-btn").style.display = "none";
    document.getElementById("check-btn").style.display = "none";
    document.getElementById("isunique-btn").style.display = "block";
    document.getElementById("solve-btn").style.display = "block";

    // change status card view
    // timer for time takes to solve grid
    // gameid show text "sudoku solver"
    // difficulty show if grid solved is unique
    document.getElementById("timer-label").innerText = "Solve time";
    document.getElementById("timer").innerText = "00:00";
    document.getElementById("game-difficulty-label").innerText = "Is unique";
    document.getElementById("game-difficulty").innerText = "Unknown";
    document.getElementById("game-number").innerText = "#Soduko_Solver"

    //focus first cell
    document.getElementById("puzzle-grid").rows[0].cells[0].getElementsByTagName('input')[0].focus();
}

function solveButtonClick() {

    if (gameOn) {
        gameOn = false;
        clearInterval(intervalId);
    }
    
    var result = solveSudoku(true);
    switch (result) {
        case 0:
            alert("SOLVED");
            break;
        case 1:
            alert("This grid is already solved")
            break;
        case 2:
            alert("This grid can't be solved because of an invalid input")
            break;
        case 3:
            alert("this grid has no solution");
            break;
    }
}

function isUniqueButtonClick() {
    // check if gird is already solved
    // if not try to solve it

    if (!isSolved) {
        if (canSolved)
            solveSudoku(false);
    }
    if (!isSolved) {
        alert("Can't check this grid because it is unsolvable!");
        return;
    }

    // solve it again but start from the end
    var columns = getColumns(puzzle);
    var blocks = getBlocks(puzzle);
    var solution2 = solveGrid(generatePossibleNumber(puzzle, columns, blocks), puzzle, false);

    // if tow solutions are equals then it is unique and vice versa
    var unique = true;
    for (var i = 0; i < solution.length; i++) {
        for (var j = 0; j < solution[i].length; j++) {
            if (solution[i][j] !== solution2[i][j]) {
                unique = false;
                break;
            }
            if (!unique)
                break;
        }
    }

    //display the result
    document.getElementById("game-difficulty").innerText = unique ? "Yes" : "No";
}
            
          
!
999px

Console