首先看一个示例:
结构:
<div class="static">默认定位
<div class="relative">相对定位
<div class="absolute">绝对定位</div>
<div class="fixed">固定定位</div>
</div>
</div>
样式:
*{padding: 0;margin: 0;}
.static{300px;height: 300px;}
.relative{margin:50px 50px; 200px;height: 200px;position: relative;top: 50px;}
.absolute{position: absolute;top: 0;left: 0; 100px;height: 100px;}
.fixed{position: fixed;top: 0;left: 0; 100px;height: 100px;}