<!-- Forum question answer only:
https://www.sitepoint.com/community/t/help-my-menu-bar-is-not-sliding/354125/3 -->
<div class="wrapper">
  <div class="container">
    <h2>Tutor</h2>
    <input type="checkbox" id="check">
    <label for="check" class="checkbutton">
      <i class="fas fa-bars">Menu</i>
    </label>
    <nav>
      <ul>
        <li><a class="active" href="#">Home</a></li>
        <li><a href="#">Services</a></li>
        <li><a href="#">Feedback</a></li>
        <li><a href="#">About Us</a></li>
        <li><a href="#">Gallery</a></li>
      </ul>
    </nav>
  </div>
</div>

/*  =======================
        general selector
    =======================   */
* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
body,
html {
  height: 100%;
}
html {
  font-size: 62.5%;
}

/*  =======================
        layout
    =======================   */
.wrapper {
  width: 100%;
  height: 8rem;
  background: #000;
}

.container {
  width: 90%;
  height: 8rem;
  margin: auto;
}

.container h2 {
  font-size: 3.7rem;
  color: white;
  line-height: 8rem;
  float: left;
  margin: 0 4rem;
}

.container .checkbutton {
  float: right;
  font-size: 3.7rem;
  line-height: 8rem;
  margin: 0 3rem;
  color: white;
  display: none;
}

nav {
  margin: 0;
  padding: 0;
}

nav ul {
  float: right;
}

nav li {
  display: inline-block;
  line-height: 8rem;
  list-style: none;
}

nav a {
  font-size: 1.8rem;
  text-decoration: none;
  color: white;
  margin: 0 1.5rem;
  text-transform: uppercase;
  font-weight: bold;
  padding: 0.3rem 0.6rem;
  border-radius: 0.4rem;
}

nav a.active,
a:hover {
  background: #32cd32;
}

#check {
  display: none;
}

/* =======================
     media queries
   ======================= */
@media only screen and (max-width: 904px) {
  .container {
    width: 100%;
  }

  .container h2 {
    font-size: 3rem;
    margin-left: 3rem;
  }

  nav a {
    font-size: 2rem;
    font-weight: bold;
    color: black;
  }

  .container .checkbutton {
    display: block;
    cursor: pointer;
  }

  nav ul {
    width: 100%;
    height: 100vh;
    position: fixed;
    top: 8rem;
    max-height:calc(100vh - 8rem);
    overflow:auto;
    text-align: center;
    left: -100%;
    transition: all 0.1s;
  }

  nav li {
    display: block;
    line-height: 10rem;
    border-bottom: 1px solid gray;
  }

  nav a.active,
  a:hover {
    background: none;
    color: grey;
  }

  #check:checked ~ nav ul {
    left: 0;
  }
}