<div>
  <ul>
    <li>メニュー1</li>
    <li>メニュー2</li>
    <li>メニュー3</li>
    <li>メニュー4</li>
    <li>長いメニュー長いメニュー長いメニュー長いメニュー5</li>
  </ul>
</div>
div{
  padding:20px;
}
ul{
  display:table;
  width:100%;
  height:60px;
  border-left:1px solid #ccc;
  border-top:1px solid #ccc;
  table-layout:fixed;
  li{
    display:table-cell;
    border-right:1px solid #ccc;
    border-bottom:1px solid #ccc;
    padding:20px;
    text-align:center;
    vertical-align:middle;
    line-height:150%;
  }
}

External CSS

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External JavaScript

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