CSS 属性的默认值

最近在看到一篇关于如何实现水平垂直居中，发现有许多属性值，自己并不了解，特此Google一番，查到，摘抄过来，方便以后查阅，下面是如何实现水平垂直居中的博文。

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解读CSS布局之-水平垂直居中

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html, address, 
blockquote, 
body, dd, div, 
dl, dt, fieldset, form, 
frame, frameset, 
h1, h2, h3, h4, 
h5, h6, noframes, 
ol, p, ul, center, 
dir, hr, menu, pre { display: block } 

li { display: list-item } 
head { display: none } 

table { display: table } 
tr { display: table-row } 
thead { display: table-header-group } 
tbody { display: table-row-group } 
tfoot { display: table-footer-group } 
col { display: table-column } 
colgroup { display: table-column-group } 
td, th { display: table-cell; } 
caption { display: table-caption } 
th { font-weight: bolder; text-align: center } 
caption { text-align: center } 

body { margin: 8px; line-height: 1.12 } 
h1 { font-size: 2em; margin: .67em 0 } 
h2 { font-size: 1.5em; margin: .75em 0 } 
h3 { font-size: 1.17em; margin: .83em 0 } 
h4, p, 
blockquote, ul, 
fieldset, form, 
ol, dl, dir, 
menu { margin: 1.12em 0 } 
h5 { font-size: .83em; margin: 1.5em 0 } 
h6 { font-size: .75em; margin: 1.67em 0 } 
h1, h2, h3, h4, 
h5, h6, b, 
strong { font-weight: bolder } 
blockquote { margin-left: 40px; margin-right: 40px } 
i, cite, em, 
var, address { font-style: italic } 
pre, tt, code, 
kbd, samp { font-family: monospace } 
pre { white-space: pre } 

button, textarea, 
input, object, 
select { display:inline-block; } 

big { font-size: 1.17em } 
small, sub, sup { font-size: .83em } 
sub { vertical-align: sub } 
sup { vertical-align: super } 

table { border-spacing: 2px; } 
thead, tbody, 
tfoot { vertical-align: middle } 
td, th { vertical-align: inherit } 
s, strike, del { text-decoration: line-through } 

hr { border: 1px inset } 
ol, ul, dir, 
menu, dd { margin-left: 40px } 
ol { list-style-type: decimal } 
ol ul, ul ol, 
ul ul, ol ol { margin-top: 0; margin-bottom: 0 } 
u, ins { text-decoration: underline } 
br:before { content: "A" } 
:before, :after { white-space: pre-line } 
center { text-align: center } 
abbr, acronym { font-variant: small-caps; letter-spacing: 0.1em } 
:link, :visited { text-decoration: underline } 
:focus { outline: thin dotted invert } 

/* Begin bidirectionality settings (do not change) */ 

BDO[DIR="ltr"] { direction: ltr; unicode-bidi: bidi-override } 
BDO[DIR="rtl"] { direction: rtl; unicode-bidi: bidi-override } 
*[DIR="ltr"] { direction: ltr; unicode-bidi: embed } 
*[DIR="rtl"] { direction: rtl; unicode-bidi: embed } 
@media print { 
h1 { page-break-before: always } 
h1, h2, h3, 
h4, h5, h6 { page-break-after: avoid } 
ul, ol, dl { page-break-before: avoid }
} 

下面附上更全的W3C
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