引入語言<link rel="stylesheet" href="css/reset.css" type="text/css" /><link rel="stylesheet" href="css/common.css" type="text/css" /><link rel="stylesheet" href="css/index.css" type="text/css" />CSS代碼body,ul,ol,li,p,h1,h2,h3,h4,h5,h6,form,fieldset,table,td,img,div,dl,dt,dd,input,{margin:0;padding:0;}body{font-size:12px;}img{border:none;}ul,ol,li{list-style:none;}input,select,textarea{outline:none;}textarea{resize:none;}a{text-decoration:none;}/*清浮動*/.clearfix:after{content:"";display:block;clear:both;}.clearfix{zoom:1;}問題：設(shè)置了margin:0;padding:0;為什么頭部的div標簽還是不緊靠上邊框和左邊框？