太奇葩了html文件里面的代码：<div class="nav"><div class="nav_right"></div><div class="nav_mid"></div><div class="nav_right"></div></div>css文件里面代码：.nav{ height:40px;}.nav_left { width: 10px; background:url(../images/nav_left.jpg) no-repeat;}.nav_mid{ width:980px; background:url(../images/nav_bg.jpg) repeat-x;}.nav_right{ width:10px; background:url(../images/nav_right.jpg) no-repeat;}.nav_left,.nav_mid,.nav_right{ float:left;  // ！！！！！！！在这里将left改为right就能水平排列了，真的太奇葩……为神马啊！ height:40px;}