title: Hamburger menu 100% height
body: <p>I'm making a responsive hamburger menu for a test app. I want the hamburger menu to occupy the entire screen (100% of the height) when it's opened.</p>
  
  <p>I tried media queries: <code>.header .menu</code> height to 100% but it doesn't work:</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 {
    margin: 0;
    font-family: Helvetica, sans-serif;
    background-color: #f4f4f4;
  }
  
  a {
    color: #8C2635;
  }
  
  a:hover {
    color: #8B8D33;
  }
  
  
  /* header */
  
  .header {
    background-color: #fff;
    position: fixed;
    height: 80px;
    width: 100%;
    z-index: 3;
  }
  
  .header ul {
    margin: 0;
    padding: 0;
    list-style: none;
    overflow: hidden;
    background-color: #fff;
  }
  
  .header li a {
    display: block;
    padding: 20px 20px;
    text-decoration: none;
  }
  
  .header .logo {
    display: block;
    float: left;
    font-size: 2em;
    padding: 10px 20px;
    text-decoration: none;
  }
  
  
  /* menu */
  
  .header .menu {
    clear: both;
    max-height: 0;
    text-align: center;
    transition: max-height .2s ease-out;
    position: relative;
    top: -7px;
  }
  
  
  /* menu icon */
  
  .header .menu-icon {
    cursor: pointer;
    display: inline-block;
    float: right;
    padding: 40px 20px;
    position: relative;
    user-select: none;
  }
  
  .header .menu-icon .navicon {
    background: #333;
    display: block;
    height: 2px;
    position: relative;
    transition: background .2s ease-out;
    width: 18px;
  }
  
  .header .menu-icon .navicon:before,
  .header .menu-icon .navicon:after {
    background: #333;
    content: '';
    display: block;
    height: 100%;
    position: absolute;
    transition: all .2s ease-out;
    width: 100%;
  }
  
  .header .menu-icon .navicon:before {
    top: 5px;
  }
  
  .header .menu-icon .navicon:after {
    top: -5px;
  }
  
  
  /* menu btn */
  
  .header .menu-btn {
    display: none;
  }
  
  .header .menu-btn:checked~.menu {
    max-height: 300px;
  }
  
  .header .menu-btn:checked~.menu-icon .navicon {
    background: transparent;
  }
  
  .header .menu-btn:checked~.menu-icon .navicon:before {
    transform: rotate(-45deg);
  }
  
  .header .menu-btn:checked~.menu-icon .navicon:after {
    transform: rotate(45deg);
  }
  
  .header .menu-btn:checked~.menu-icon:not(.steps) .navicon:before,
  .header .menu-btn:checked~.menu-icon:not(.steps) .navicon:after {
    top: 0;
  }
  
  @media (min-width: 64em) {
    .header li {
      float: left;
    }
    .header li a {
      padding: 30px 30px;
    }
    .header .menu {
      clear: none;
      float: right;
      max-height: none;
    }
    .header .menu-icon {
      display: none;
    }
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;header class="header"&gt;
  
    &lt;input class="menu-btn" type="checkbox" id="menu-btn" /&gt;
    &lt;label class="menu-icon" for="menu-btn"&gt;&lt;span class="navicon"&gt;&lt;/span&gt;&lt;/label&gt;
  
    &lt;ul class="menu"&gt;
      &lt;li&gt;&lt;a href="#work"&gt;HOME&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a href="#about"&gt;SOBRE NÓS&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a href="#careers"&gt;OBJETIVOS&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a href="#contact"&gt;PARCEIROS&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a href="#contact"&gt;CONTACTOS&lt;/a&gt;&lt;/li&gt;
    &lt;/ul&gt;
  
  &lt;/header&gt;</code></pre>
  </div>
  </div>
  </p>