title: DIV's side by side within a container
body: <p>I am working on an internal program for work that is essentially built on PHP. My problem is that I have a a header, a side navigation, the main content (to the right of the nav) and a footer. <a href="https://i.stack.imgur.com/whLdr.png" rel="nofollow noreferrer">Rough Layout Picture</a></p>
  
  <p>My issue is that I have two DIV's within a container, the nav is set to a percentage with a minimum width, and the content section is set to take the remaining space. In total both the nav and content should take about 91% of the screen real estate. <a href="https://i.stack.imgur.com/qhwwU.png" rel="nofollow noreferrer">Whats Happening after shrinking the browser a bit</a></p>
  
  <p>My CSS looks like this for the fields I think are relevant:</p>
  
  <pre><code>    .container{
          width: 100%;
          float: inline-block;
      }
      .header{
          float: left;
          text-align: left;
          background-color: lightblue;
          width: 100%;
          vertical-align: middle;
          display: block;
          border-radius: 15px;
      }
      .header h1{
          font-weight: bold;
          font-size: 40px;
          text-indent: 50px;
      }
      .msg_alert{
          background-color: green;
          color: white;
          width: 95%;
          padding: 5px;
          border-radius: 10px;
      }
      .err_msg_alert{
          background-color: red;
          color: white;
          width: 95%;
          padding: 5px;
          border-radius: 10px;
      }
      .menu{
          float: left;
          width: 13%;
          border: 3px solid grey;
          padding: 5px;
          background-color: lightgrey;
          border-radius: 15px;
          margin-top: 20px;
          margin-right: 20px;
          min-width: 200px;
      }
      .menu a{
          float: left;
          color: black;
          text-align: left;
          padding: 14px;
          text-decoration: none;
          box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
          margin: 3px;
          background-color: lightblue;
          width: 40%;
          min-width: 150px;
          border-radius: 15px;
      }
      .menu a:hover{
          background-color: grey;
          color: black;
      }
      .menu ul{
          list-style-type: none;
          margin: 0;
          padding: 0;
      }
      .menu li{
          padding: 8px;
          margin-bottom: 7px;
      }
      .content{
          float: left;
          width: 78%;
          padding: 20px;
          margin-top: 20px;
          margin-left: 20px;
          /*border: 3px solid red;*/
      }
      .footer{
          display: inline-block;
          width: 100%;
          background-color: lightgrey;
          border-radius: 15px;
          font-size: 12px;
          text-align: center;
          margin-top: 5px;
          padding-bottom: 10px;
      }
  </code></pre>
  
  <p>I'm not sure what I've done wrong. Everything displays properly if the browser is in full screen but when I shrink it down to about 3/4's of the browser size the nav stays where it should be but the contents move below. </p>
  
  <p>I have setup a mobile version which works perfectly but the desktop mode is what I am having issues with.</p>
  
  <p>Thank you for the help in advance.</p>