css面试点-为什么要初始化css样式

浏览器差异：

不同浏览器对有些标签的默认值是不同的，如果没对css初始化会出现浏览器之间的页面显示差异
 

提高编码质量：

如果不初始化，整个页面做完会很糟糕，重复的css样式很多。去掉标签的默认样式如：margin,padding，其他浏览器默认解析字体大小，字体设置。
 

淘宝样式 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; }
fieldset, img { border:0; }
button, input, select, textarea { font-size:100%; }
table { border-collapse:collapse; border-spacing:0; }

腾讯QQ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}

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;}

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;}