title: Problems in displaying a form by selecting a Tab in HTML & CSS?
body: <p>I am learning how to use tabs and opening content by selecting a Tab. So far it works fine but when I try to display a form (such as inputbox,buttons etc) by clicking a tab, it doesn't display anything. Where am I doing wrong?</p>
  
  <h2>HTML section</h2>
  
  <pre><code>&lt;html&gt;
      &lt;head&gt;
       &lt;link rel="stylesheet" href="css/menu.css"&gt;
  
  
      &lt;/head&gt;
  &lt;h1&gt;Responsive CSS Tabs&lt;/h1&gt;
  
  &lt;main&gt;
  
    &lt;input id="tab1" type="radio" name="tabs" checked&gt;
    &lt;label for="tab1"&gt;Home&lt;/label&gt;
  
    &lt;input id="tab2" type="radio" name="tabs"&gt;
    &lt;label for="tab2"&gt;Project&lt;/label&gt;
  
    &lt;input id="tab3" type="radio" name="tabs"&gt;
    &lt;label for="tab3"&gt;About us&lt;/label&gt;
  
    &lt;input id="tab4" type="radio" name="tabs"&gt;
    &lt;label for="tab4"&gt;Contact&lt;/label&gt;
  
    &lt;section id="content1"&gt;
      &lt;p&gt;
       This is the Home Tab
      &lt;/p&gt;
    &lt;/section&gt;
  
    &lt;section id="content2"&gt;
        &lt;html&gt;
        &lt;form&gt;
         &lt;label for="Project Name"&gt;Project Name&lt;/label&gt;
         &lt;br/&gt;
         &lt;input type="text" id="ProjectName"&gt;
         &lt;br/&gt;   
         &lt;label for="Project Manager"&gt;Project Manager&lt;/label&gt;
      &lt;br/&gt;
          &lt;input type="text" id="ProjectManager"&gt;
          &lt;br/&gt;
          &lt;input type="text" id="Start Date"&gt;
  
  
  
  
  
        &lt;/form&gt;
        &lt;/html&gt;
  
  
    &lt;/section&gt;
  
    &lt;section id="content3"&gt;
      &lt;p&gt;
       This is the about us page.
      &lt;/p&gt;
    &lt;/section&gt;
  
    &lt;section id="content4"&gt;
      &lt;p&gt;
      This is the Contact Us section.
      &lt;/p&gt;
    &lt;/section&gt;
  
  &lt;/main&gt;
  &lt;/html&gt;
  </code></pre>
  
  <h2>CSS code</h2>
  
  <pre><code>@import url('http://fonts.googleapis.com/css?family=Open+Sans:400,600,700');
  @import url('http://netdna.bootstrapcdn.com/font-awesome/4.1.0/css/font-awesome.css');
  
  *, *:before, *:after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  html, body {
    height: 100%;
  }
  
  body {
    font: 14px/1 'Open Sans', sans-serif;
    color: #555;
    background: #eee;
  }
  
  h1 {
    padding: 50px 0;
    font-weight: 400;
    text-align: center;
  }
  
  p {
    margin: 0 0 20px;
    line-height: 1.5;
  }
  
  main {
    min-width: 320px;
    max-width: 800px;
    padding: 50px;
    margin: 0 auto;
    background: #fff;
  }
  
  section {
    display: none;
    padding: 20px 0 0;
    border-top: 1px solid #ddd;
  }
  
  input {
  display: none;
  
  }
  
  #content2 input {
    display: block;
  }
  
  label {
    display: inline-block;
    margin: 0 0 -1px;
    padding: 15px 25px;
    font-weight: 600;
    text-align: center;
    color: #bbb;
    border: 1px solid transparent;
  }
  
  label:before {
    font-family: fontawesome;
    font-weight: normal;
    margin-right: 10px;
  }
  
  label[for*='1']:before { content: '\f1cb'; }
  label[for*='2']:before { content: '\f17d'; }
  label[for*='3']:before { content: '\f16b'; }
  label[for*='4']:before { content: '\f1a9'; }
  
  label:hover {
    color: #888;
    cursor: pointer;
  }
  
  input:checked + label {
    color: #555;
    border: 1px solid #ddd;
    border-top: 2px solid orange;
    border-bottom: 1px solid #fff;
  }
  
  #tab1:checked ~ #content1,
  #tab2:checked ~ #content2,
  #tab3:checked ~ #content3,
  #tab4:checked ~ #content4 {
    display: block;
  }
  
  @media screen and (max-width: 650px) {
    label {
      font-size: 0;
    }
    label:before {
      margin: 0;
      font-size: 18px;
    }
  }
  
  @media screen and (max-width: 400px) {
    label {
      padding: 15px;
    }
  }
  </code></pre>