title: <div> doesn't take the full height of the page
body: <p>I am trying to make the 4 colums with the class <code>.column</code> to be 100% of the page's height, but can't do it and I have no idea why. </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>body,
  html {
    margin: 0px;
    padding: 0px;
    font-family: Helvetica, sans-serif;
    height: 100%;
    width: 100%;
  }
  #header {
    height: 40px;
    width: 100%;
    background-color: grey;
    display: block;
  }
  #logo {
    float: left;
    font-size: 30px;
    font-weight: bold;
    padding-left: 15;
    padding-top: 3px;
    margin: 0 auto;
    width: 10%;
  }
  #menu {
    margin: 0 auto;
    width: 50%;
    height: 50%;
    padding: 10px;
    text-align: center;
  }
  #menu li {
    display: inline;
    border: 1px solid black;
    border-radius: 15%;
    background-color: red;
    color: white;
  }
  #menu a {
    text-decoration: none;
    padding: 0 10px;
    /* variable width */
  }
  a:hover {
    background-color: black;
  }
  a:link,
  a:visited,
  a:active {
    color: white;
  }
  .column {
    top: 0;
    left: 0;
    margin: 0;
    padding: 0;
    width: 25%;
    height: 100%;
    float: left;
    -webkit-box-shadow: inset 0px 0px 0px 1px black;
    -moz-box-shadow: inset 0px 0px 0px 1px black;
    box-shadow: inset 0px 0px 0px 1px black;
  }
  .clear-div {
    clear: both;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div id="header"&gt;
  
    &lt;div id="logo"&gt;
      CodePlayer
    &lt;/div&gt;
  
    &lt;div id="menu"&gt;
      &lt;li&gt;&lt;a href="#"&gt;HTML&lt;/a&gt;
      &lt;/li&gt;
      &lt;li&gt;&lt;a href="#"&gt;CSS&lt;/a&gt;
      &lt;/li&gt;
      &lt;li&gt;&lt;a href="#"&gt;JAVASCRIPT&lt;/a&gt;
      &lt;/li&gt;
      &lt;li&gt;&lt;a href="#"&gt;OUTPUT&lt;/a&gt;
      &lt;/li&gt;
    &lt;/div&gt;
  
    &lt;div class="clear-div"&gt;
  
    &lt;/div&gt;
  
    &lt;div class="column" id="html"&gt;
      This column needs to be 100% of the page's height
    &lt;/div&gt;
    &lt;div class="column" id="css"&gt;
      This column needs to be 100% of the page's height
    &lt;/div&gt;
    &lt;div class="column" id="javascript"&gt;
      This column needs to be 100% of the page's height
    &lt;/div&gt;
    &lt;div class="column" id="output"&gt;
      This column needs to be 100% of the page's height
    &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>I am a beginner and every advice on good web developement practices will be very valuable to me so if there's something that I could've have done better please let me know.</p>