腾讯官网样式初始化

body,ol,ul,h1,h2,h3,h4,h5,h6,p,th,td,dl,dd,form,fieldset,legend,input,textarea,select{margin:0;padding:0} 
body{font:12px"宋体","Arial Narrow",HELVETICA;background:#fff;-webkit-text-size-adjust:100%;} 
a{color:#2d374b;text-decoration:none} 
a:hover{color:#cd0200;text-decoration:underline} 
em{font-style:normal} 
li{list-style:none} 
img{border:0;vertical-align:middle} 
table{border-collapse:collapse;border-spacing:0} 
p{word-wrap:break-word}
.cl:after{
    content:"";
    display:block;
    overflow:hidden;
    clear:both;
    height:0;
    visibility:hidden;
}
.cl{
    zoom:1;
}
.Flex{
	display: flex;
	display: -webkit-box; 
	display: -moz-box; 
	display: -webkit-flex; 
	display: -moz-flex; 
	display: -ms-flexbox; 
}

雅虎工程师提供的CSS初始化示例代码

body,div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,code,form,fieldset,legend,input,button,textarea,p,blockquote,th,td { margin:0; padding:0; }
body { background:#fff; color:#555; font-size:14px; font-family: Verdana, Arial, Helvetica, sans-serif; }
td,th,caption { font-size:14px; }
h1, h2, h3, h4, h5, h6 { font-weight:normal; font-size:100%; }
address, caption, cite, code, dfn, em, strong, th, var { font-style:normal; font-weight:normal;}
a { color:#555; text-decoration:none; }
a:hover { text-decoration:underline; }
img { border:none; }
ol,ul,li { list-style:none; }
input, textarea, select, button { font:14px Verdana,Helvetica,Arial,sans-serif; }
table { border-collapse:collapse; }
html {overflow-y: scroll;}

.clearfix:after {content: "."; display: block; height:0; clear:both; visibility: hidden;}
.clearfix { *zoom:1; }
.Flex{
	display: flex;
	display: -webkit-box; 
	display: -moz-box; 
	display: -webkit-flex; 
	display: -moz-flex; 
	display: -ms-flexbox; 
}

新浪官网样式初始化

body,ul,ol,li,p,h1,h2,h3,h4,h5,h6,form,fieldset,table,td,img,div{margin:0;padding:0;border:0;} 
body{background:#fff;color:#333;font-size:12px; margin-top:5px;font-family:"SimSun","宋体","Arial Narrow";} 
 
ul,ol{list-style-type:none;} 
select,input,img,select{vertical-align:middle;} 
 
a{text-decoration:none;} 
a:link{color:#009;} 
a:visited{color:#800080;} 
a:hover,a:active,a:focus{color:#c00;text-decoration:underline;}
.cl:after{
    content:"";
    display:block;
    overflow:hidden;
    clear:both;
    height:0;
    visibility:hidden;
}
.cl{
    zoom:1;
}
.Flex{
	display: flex;
	display: -webkit-box; 
	display: -moz-box; 
	display: -webkit-flex; 
	display: -moz-flex; 
	display: -ms-flexbox; 
}

淘宝官网样式初始化

body, h1, h2, h3, h4, h5, h6, hr, p, blockquote, dl, dt, dd, ul, ol, li, pre, form, fieldset, legend, button, input, textarea, th, td { margin:0; padding:0; } 
<!--body, button, input, select, textarea { font:12px/1.5tahoma, arial, \5b8b\4f53; } -->
<!--h1, h2, h3, h4, h5, h6{ font-size:100%; } -->
address, cite, dfn, em, var { font-style:normal; } 
code, kbd, pre, samp { font-family:couriernew, courier, monospace; } 
small{ font-size:12px; } 
ul, ol { list-style:none; } 
a { text-decoration:none; } 
a:hover { text-decoration:underline; } 
sup { vertical-align:text-top; } 
sub{ vertical-align:text-bottom; } 
legend { color:#000; } 
img { border:0; } 
button, input, select, textarea { font-size:100%; }
table { border-collapse:collapse; border-spacing:0; }
.cl:after{
    content:"";
    display:block;
    overflow:hidden;
    clear:both;
    height:0;
    visibility:hidden;
}
.cl{
    zoom:1;
}
.Flex{
	display: flex;
	display: -webkit-box; 
	display: -moz-box; 
	display: -webkit-flex; 
	display: -moz-flex; 
	display: -ms-flexbox; 
}

网易官网样式初始化

html {overflow-y:scroll;} 
body {margin:0; padding:29px00; font:12px"\5B8B\4F53",sans-serif;background:#ffffff;} 
div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,form,fieldset,input,textarea,blockquote,p{padding:0; margin:0;} 
table,td,tr,th{font-size:12px;} 
li{list-style-type:none;} 
img{vertical-align:top;border:0;} 
ol,ul {list-style:none;} 
h1,h2,h3,h4,h5,h6{font-size:12px; font-weight:normal;} 
address,cite,code,em,th {font-weight:normal; font-style:normal;}
.cl:after{
    content:"";
    display:block;
    overflow:hidden;
    clear:both;
    height:0;
    visibility:hidden;
}
.cl{
    zoom:1;
}
.Flex{
	display: flex;
	display: -webkit-box; 
	display: -moz-box; 
	display: -webkit-flex; 
	display: -moz-flex; 
	display: -ms-flexbox; 
}