内联级内容

<p>
  This span is an <span class="highlight">inline-level element</span>; its
  background has been colored to display both the beginning and end of the
  element's influence. Input elements, like <input type="radio" /> and
  <input type="checkbox" />, are also inline-level content.
</p>

body {
  margin: 0;
  padding: 4px;
  border: 1px solid #333333;
}

.highlight {
  background-color: #eeee33;
}