为什么加了给 a标签加了左右的padding之后为什么宽度会不断的增加
求解释为什么加了给 a标签加了左右的padding之后为什么宽度会不断的增加
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>导航菜单</title> <style type="text/css"> *{margin:0; padding:0; font-size:14px;} a{color:#333;text-decoration:none ;padding:5px;} //注意这里的padding .nav{list-style:none; height:30px; border-bottom:10px solid #F60; margin-top:20px; padding-left:50px;} .nav li{float:left} .nav li a{display:block; height:30px;text-align:center; line-height:30px; width:80px; background:#efefef; margin-left:1px;} .nav li a.on, .nav li a:hover{background:#F60;color:#fff; } </style> <script> window.onload=function(){ var oNav=document.getElementsByTagName('ul')[0]; var aA=oNav.getElementsByTagName('a'); for(var i=0; i<aA.length; i++){ aA[i].onmouseover=function(){ if(this.className!="on"){ clearInterval(this.time); var This=this; This.time=setInterval(function(){ This.style.width=This.offsetWidth+8+"px"; if(This.offsetWidth>=120) clearInterval(This.time); },30) } } aA[i].onmouseout=function(){ if(this.className!="on"){ clearInterval(this.time); var This=this; this.time=setInterval(function(){ This.style.width=This.offsetWidth-8+"px"; if(This.offsetWidth<=80){ This.style.width='80px'; clearInterval(This.time); } },30) } } } } </script> </head> <body> <ul class="nav"> <li><a class="on" href="#">首 页</a></li> <li><a href="#">关于我们</a></li> <li><a href="#">产品展示</a></li> <li><a href="#">售后服务</a></li> <li><a href="#">联系我们</a></li> </ul> </body> </html>