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/* Basics */
/* styling basics */
html {padding: 20px 0; background-color: #efefef;}
body {width: 80%; padding: 40px; margin: 0 auto; background: #fff; box-shadow: 1px 1px 5px rgba(0,0,0,0.5); font-family: Verdana, Arial, sans-serif; font-size: 14px;}

/* Einfach mal hübsch machen mit einem YAML4-Standard-Style */
    table{width:100%;border-collapse:collapse;margin:1.3571em 0 0 0;color:#333;border-top:1px #ccc solid;border-bottom:1px #ccc solid;}
    table caption{font-variant:small-caps;}
    th,td{line-height:1.5em;vertical-align:top;padding:0.7143em 0.5em; text-align:left; color: #000;}

    thead th{border-bottom:2px #000 solid;}
    tbody th{border-top:1px solid #ccc;}
    tbody td{border-top:1px solid #ccc;}
    tbody tr:hover th,
    tbody tr:hover td{background:#f1f1f1;}

/* geht nicht */
/*    td:not(tbody tr:first-child  td:first-of-type):not(tbody tr:last-child td:last-of-type){background: yellow} */

tbody td {background: yellow;}
tbody tr:first-child td:first-child,
tbody tr:last-child td:last-child{background: none;}

      <table>
          <thead>
              <tr>
                <th>Entry Header 1</th>
                <th>Entry Header 2</th>
                <th>Entry Header 3</th>
                <th>Entry Header 4</th>
              </tr>
          </thead>
          <tbody>
              <tr>
                <td>Entry First Line 1</td>
                <td>Entry First Line 2</td>
                <td>Entry First Line 3</td>
                <td>Entry First Line 4</td>
              </tr>
              <tr>
                <td>Entry Line 1</td>
                <td>Entry Line 2</td>
                <td>Entry Line 3</td>
                <td>Entry Line 4</td>
              </tr>
              <tr>
                <td>Entry Last Line 1</td>
                <td>Entry Last Line 2</td>
                <td>Entry Last Line 3</td>
                <td>Entry Last Line 4</td>
              </tr>
          </tbody>
      </table>