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HTML

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CSS

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JavaScript

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HTML 

              
                <!DOCTYPE html>
<html>
<head>
   <meta charset="utf-8">
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>Mastering RWD with HTML5 &amp; CSS3</title>
   <link rel="stylesheet" href="css/site-styles.css">
</head>
<body>
<header class="masthead" role="banner">
   <div class="logo">Mastering RWD with HTML5 &amp; CSS3</div>
   <div class="search" role="search">
      <form>
         <label>Search:
            <input type="text" class="field">
            <button>Search Now!</button>
         </label>
      </form>
   </div>
</header>
   <nav class="main-nav" role="navigation">
      <ul class="nav-container">
         <li><a href="#">Link 1</a></li>
         <li><a href="#">Link 2</a></li>
         <li><a href="#">Link 3</a></li>
         <li><a href="#">Link 4</a></li>
      </ul>
   </nav>
   <main class="main-container" role="main">
      <h1>Chapter 2: Marking Our Content with HTML5</h1>
      <p>Many consider that HTML is “code”. Well, it’s not. HTML, any version of it, is a “markup” language. </p>
      <article class="article-container flex-container">
         <section class="main-content">
            <header>
               <h1>The <code>&lt;main></code> element  </h1>
            </header>
            <p>As per the MDN definition:</p>
            <blockquote>
               <p>The HTML Main Element (<code>&lt;main></code>) represents&hellip;</p>
            </blockquote>
         </section>
         <aside class="side-content" role="complementary">
            <h2>What Does “Semantic HTML” Mean?</h2>
            <p>Semantic markup basically means that we use HTML tags to describe what a specific piece of content is.</p>
         </aside>
      </article>
      <div class="contact-form" role="form">
         <header>
            <h2>Have Questions About HTML5?</h2>
         </header>
         <form>
            <div class="flex-container">
               <label class="label-col">Name: <input type="text" class="field name" id="name" required></label>
               <label class="label-col">Email: <input type="email" class="field email" id="email" required></label>
            </div>
            <label for="comments">Comments:</label>
            <textarea class="comments" id="comments" cols="50" required></textarea>
            <button>Send Question!</button>
         </form>
      </div>
<footer class="main-footer" role="contentinfo">
   <p>Copyright &copy;</p>
   <ul class="nav-container" role="navigation">
      <li><a href="#">Footer Link 1</a></li>
      <li><a href="#">Footer Link 2</a></li>
      <li><a href="#">Footer Link 3</a></li>
      <li><a href="#">Footer Link 4</a></li>
      <li><a href="#">Footer Link 5</a></li>
   </ul>
</footer>
   </main>
</body>
</html>
<!--
<body>
   <header class="masthead" role="banner">
      <div class="logo">Mastering RWD with HTML5 &amp; CSS3</div>
<div class="search" role="search">
   <form>
      <label>Search:
         <input type="text" class="field">
         <button>Search Now!</button>
      </label>
   </form>
</div>
   </header>
   <nav class="main-nav" role="navigation">
      <ul class="nav-container">
         <li><a href="#">Link 1</a></li>
         <li><a href="#">Link 2</a></li>
         <li><a href="#">Link 3</a></li>
         <li><a href="#">Link 4</a></li>
      </ul>
   </nav>
   <main class="main-container" role="main">
      <article class="article-container flex-container">
         <section class="main-content">
            <header>
               <h1>The <code>&lt;main></code> element</h1>
            </header>
            <p>As per the MDN definition:</p>
            <blockquote>
               <p>The HTML Main Element (<code>&lt;main></code>) represents&hellip;</p>
            </blockquote>
         </section>
         <aside class="side-content" role="complementary">
            <h2>What Does “Semantic HTML” Mean?</h2>
            <p>Semantic markup basically means that we use HTML tags to describe what a specific piece of content is.</p>
         </aside>
      </article>
      <footer class="main-footer" role="contentinfo">
         <p>Copyright &copy;</p>
         <ul class="nav-container" role="navigation">
            <li><a href="#">Footer Link 1</a></li>
            <li><a href="#">Footer Link 2</a></li>
            <li><a href="#">Footer Link 3</a></li>
            <li><a href="#">Footer Link 4</a></li>
            <li><a href="#">Footer Link 5</a></li>
         </ul>
      </footer>
   </main>
</body>-->
!

CSS 

              
                //Media Query Mixin - Desktop-first
@mixin forSmallScreens($media) {
   @media (max-width: $media/16+em) { @content; }
}

//Nav
.main-nav {
   max-width: 980px;
   margin: auto;
   padding: 10px 5px;
   background: #555;
   @include forSmallScreens(420) {
      padding: 5px 0;
   }
}

//All Navigations
.nav-container {
   display: flex;
   justify-content: center;
   list-style-type: none;
   margin: 0;
   padding: 0;
   @include forSmallScreens(420) {
      flex-wrap: wrap;
   }
   li {
      display: flex;      
      width: 100%;
      margin: 0 5px;
      text-align: center;
      @include forSmallScreens(420) {
         display: flex;
         justify-content: center;
         flex-basis: 45%;
         margin: 5px;
      }
   }
   a {
      @extend %highlight-section;
      display: flex;
      justify-content: center;
      align-items: center;
      width: 100%;
      padding: 10px;
      color: white;
   }
}

//Header
.masthead {
   display: flex;
   justify-content: space-between;
   max-width: 980px;
   margin: auto;
   padding: 10px;
   background: #333;
   border-radius: 3px 3px 0 0;
   @include forSmallScreens(700) {
      display: block;
      text-align: center;
   }
}

.logo {
   @extend %highlight-section;
   padding: 0 10px;
   color: white;
   line-height: 2.5;   
   @include forSmallScreens(420) {
      font-size: .85em;
   }
}

//Search field
.search {
   @extend %highlight-section;
   padding: 5px;
   color: white;   
   @include forSmallScreens(420) {
      font-size: .85em;
   }
   .field {
      width: auto;
      margin: 0 10px 0 0;
   }
   button {
      @include forSmallScreens(420) {
         width: 100%;
         margin-top: 10px;
      }
   }
}

//Main Container
.main-container {
   max-width: 980px;
   margin: auto;
   padding: 10px;
   background: #999;
   border-radius: 0 0 3px 3px;
}

//Article
.article-container {
   @extend %highlight-section;
   margin-bottom: 20px;
   padding: 10px;   
}

   //Main Content of the Page
   .main-content {
      @extend %highlight-section;
      width: 75%;
      margin-right: 10px;
      padding: 10px;
      @include forSmallScreens(600) {
         width: 100%;
      }
      h1 {
         margin: 0;
      }
   }

   //Side Content
   .side-content {
      @extend %highlight-section;
      width: 25%;
      padding: 10px;
      font-size: .8em;
      background: #999;
      @include forSmallScreens(600) {
         width: 100%;
         margin-top: 12px;
      }
      h2 {
         margin: 0;
      }
      ol {
         padding-left: 20px;
      }
      a {
         color: #eee;
      }
   }

//Contact Form
.contact-form {
   @extend %highlight-section;
   width: 540px;
   margin: 0 auto 20px;
   padding: 20px;
   @include forSmallScreens(600) {
      width: 100%;
   }
   h2 {
      margin-top: 0;
   }
   label, button {
      display: block;
   }
   .comments {
      height: 100px;
   }
   .flex-container {
      justify-content: space-between;
      @include forSmallScreens(600) {
         display: flex;
      }
      @include forSmallScreens(400) {
         display: block;
      }
   }
   .label-col {
      width: 48%;
      @include forSmallScreens(400) {
         width: 100%;
      }
   }
}

//Form Elements
.field,
.comments {
   width: 100%;
   margin-bottom: 10px;
   padding: 5px;
   @include forSmallScreens(420) {
      width: 100%;
   }
}

//Footer
.main-footer {
   color: white;
   padding: 10px;
   background: #333;
   p {
      margin-top: 0;
   }
}

//Placeholder
%highlight-section {
   border: white 1px solid;
   border-radius: 3px;
   background: rgba(white, .1);
}

//Helper Classes
.flex-container {
   display: flex;
   @include forSmallScreens(600) {
      display: block;
   }
}

//General
*,
*:before,
*:after {
   box-sizing: border-box;
}

body {
   font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
}

blockquote {
   font-style: italic;
}
!

JS
!
999px

Console