网页布局图片背景与img标签使用

<h1 class="logo">
  <!-- 注意 a 标签不要加 title，会造成部分读屏软件重复读取 -->
  <a tabindex="2" accesskey="1" href="#">
    <img src="http://www.w3.org/2008/site/images/logo-w3c-screen-lg" alt="W3C">
    <span class="alt-logo">W3C</span>
  </a>
</h1>

.logo a {
  background: url(http://www.w3.org/2008/site/images/logo-w3c-screen-lg) no-repeat 0 0;
  display: block;
  width: 249px;
  height: 107px;
  position: relative;
  overflow: hidden;
  margin: 10px auto;
}

.logo img {
  color: #fff;
}

.logo .alt-logo {
  position: absolute;
  z-index: -1;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  padding-left: 22px;
  padding-top: 25px;
  font-size: 50px;
  color: #fff;
  background-color: #075F9F;
}