CSS 图片替换文字方案

<h2>
    <span>Hello World</span>
</h2>

h2 {
    background:url(hello_world.gif) no-repeat;
    width: 150px;
    height: 35px;
}
span {
    display: none;
}

<h2>
Hello World
</h2>

h2 {
    text-indent: -5000px;
    background:url(hello_world.gif) no-repeat;
    width: 150px;
    height:35px;
}

<h2>
    <span></span>Hello World
</h2>

h2 {
    width: 150px;
    height: 35px;
    position: relative;
}
h2 span {
    background: url(hello_world.gif) no-repeat;
    position: absolute;
    width: 100%;
    height: 100%;
}