我给#main加的margin-top啊 为什么#nav会掉下来？
<!DOCTYPE html><html><head>
<title></title>
<style type="text/css">
*{margin:0 ;padding:0} html, body { position: relative; height: 100%;
} html{-webkit-text-size-adjust:none;} #nav{width: 100%;height: 50px;background-color: blue;position: fixed;z-index: 999999999;} #main{min-height: 100%;width: 100%;margin-top: 50px} </style></head><body><div id="nav"></div><div id="main"></div></body></html>