最耗资源的，最简单的
* { padding: 0margin: 0border: 0}
选择性初始化举例（综合）
body,div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,code,legend,button
form,fieldset,input,textarea,p,blockquote,th,td {
padding: 0
margin: 0
}
3. 参考新浪、雅虎
/* 新浪全局样式 */
body,ul,ol,li,p,h1,h2,h3,h4,h5,h6,form,fieldset,table,td,img,div{
margin:0padding:0border:0
}
body{
background:#fffcolor:#333font-size:12pxmargin-top:5pxfont-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:#c00text-decoration:underline}
/* 雅虎全局样式 */
html {
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
}
浏览器里都有一个默认的margin和padding值，不同的浏览器值不相同，所以按照自己写的CSS计算宽度不对，在CSS样式开始的时候设置*{margin:0padding:0}；初始化所有元素的margin和padding为0，这样计算 的时候宽度就是设置的width，border，padding，margin值的和。你可以在CSS中加入*{padding:0margin:0}就会正常了。
