一、初始化CSS的作用：

       由于不同的浏览器对CSS的初始化不同，会造成不同的效果。因此每次新开发网站或新网页时候我们通过初始化CSS样式的属性，为我们将用到的CSS或 html标签更加方便准确，为我们节约网页代码，节约网页下载时间；还会使得我们开发网页内容时更加方便简洁，不用考虑很多。

二、需要初始化地方：

        初始化的项一般包括margin，border，padding，color，font等等，大致需要初始化有h1到h4标签、table、文字大小、文字没有链接颜色、超链接样式、DIV、居中、ol、 ul、li、img等等的样式。

三、一些css初始化例子

* { padding: 0; margin: 0; border: 0; } 

html {https://www.yahoo.com/
    background: none repeat scroll 0 0 #FFFFFF;
    color: #000000;
}
body, div, dl, dt, dd, ul, ol, li, h1, h2, h3, h4, h5, h6, pre, code, form, fieldset, legend, input, textarea, p, blockquote, th, td {
    margin: 0;
    padding: 0;
}
table {
    border-collapse: collapse;
    border-spacing: 0;
}
fieldset, img {
    border: 0 none;
}
address, caption, cite, code, dfn, em, strong, th, var {
    font-style: normal;
    font-weight: normal;
}
li {
    list-style: none outside none;
}
caption, th {
    text-align: left;
}
h1, h2, h3, h4, h5, h6 {
    font-size: 100%;
    font-weight: normal;
}
q:before, q:after {
    content: "";
}
abbr, acronym {
    border: 0 none;
    font-variant: normal;
}
sup {
    vertical-align: text-top;
}
sub {
    vertical-align: text-bottom;
}
input, textarea, select {
    font-family: inherit;
    font-size: inherit;
    font-weight: inherit;
}
input, textarea, select {
}
legend {
    color: #000000;
}
body {
    font: 13px/1.231 arial,helvetica,clean,sans-serif;
}
select, input, button, textarea {
    font: 99% arial,helvetica,clean,sans-serif;
}
table {
    font-size: inherit;
}
pre, code, kbd, samp, tt {
    font-family: monospace;
    line-height: 100%;
}
a {
    text-decoration: none;
}
a:hover, a:focus {
    text-decoration: underline;
}
strong {
    font-weight: bold;
}
input[type="submit"] {
    cursor: pointer;
}
button {
    cursor: pointer;
}

腾讯QQ官网(http://www.qq.com)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(http://www.sina.com.cn/)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;}

淘宝官网(http://www.taobao.com/)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; }

网易官网(http://www.163.com/)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;}

博客园(http://www.cnblogs.com/)初始化

/*version: 2.7.0*/
html,body{color:#000;background:#FFF;}
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;
}
table{border-collapse:collapse;border-spacing:0;}
fieldset,img{border:0;}
address,caption,cite,code,dfn,em,strong,th,var,optgroup{
    font-style:inherit;font-weight:inherit;
}
del,ins{text-decoration:none;}
li{list-style:none;}
caption,th{text-align:left;}
h1,h2,h3,h4,h5,h6{    font-size:100%;font-weight:normal;}
q:before,q:after{content:‘‘;}
abbr,acronym{border:0;font-variant:normal;}
sup{vertical-align:baseline;}
sub{vertical-align:baseline;}
legend{color:#000;}
input,button,textarea,select,optgroup,option{
    font-family:inherit;font-size:inherit;font-style:inherit;font-weight:inherit;
}
input,button,textarea,select{*font-size:100%;}
.clear{clear:both;}
input::-moz-focus-inner{ border: 0;padding: 0;}

/*added*/
input[type=button],input[type=submit] {-webkit-appearance: button;}