虽然w3c制订了html的一些标准：浏览器们都会按照自己预定义的样式来解析渲染网页中的标签，firefox可以通过在地址栏里输入resource://gre/res/html.css的命令来得到firefox的默认样式表。要是ie也有这个命令该多好！你也可以在不同版本的firefox地址栏输入这个命令，这样就可以对比firefox不同版本的差异，这让我们在Reset CSS的时候有了重要的参考。
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Blake Ross <BlakeR1234@aol.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
@namespace url(http://www.w3.org/1999/xhtml);

[dir="rtl"] {
direction: rtl;
unicode-bidi: embed;
}
[dir="ltr"] {
direction: ltr;
unicode-bidi: embed;
}
bdo[dir] {
unicode-bidi: bidi-override;
}

html, div, map, dt, isindex, form {
display: block;
}
body {
display: block;
margin: 8px;
}
p, dl, multicol {
display: block;
margin: 1em 0;
}
dd {
display: block;
-moz-margin-start: 40px;
}
blockquote {
display: block;
margin: 1em 40px;
}
address {
display: block;
font-style: italic;
}
center {
display: block;
text-align: -moz-center;
}
blockquote[type=cite] {
display: block;
margin: 1em 0px;
-moz-padding-start: 1em;
-moz-border-start: solid;
border-color: blue;
border-width: thin;
}
span[_moz_quote=true] {
color: blue;
}
pre[_moz_quote=true] {
color: blue;
}
h1 {
display: block;
font-size: 2em;
font-weight: bold;
margin: .67em 0;
}
h2 {
display: block;
font-size: 1.5em;
font-weight: bold;
margin: .83em 0;
}
h3 {
display: block;
font-size: 1.17em;
font-weight: bold;
margin: 1em 0;
}
h4 {
display: block;
font-weight: bold;
margin: 1.33em 0;
}
h5 {
display: block;
font-size: 0.83em;
font-weight: bold;
margin: 1.67em 0;
}
h6 {
display: block;
font-size: 0.67em;
font-weight: bold;
margin: 2.33em 0;
}
listing {
display: block;
font-family: -moz-fixed;
font-size: medium;
white-space: pre;
margin: 1em 0;
}
xmp, pre, plaintext {
display: block;
font-family: -moz-fixed;
white-space: pre;
margin: 1em 0;
}

table {
display: table;
border-spacing: 2px;
border-collapse: separate;
margin-top: 0;
margin-bottom: 0;

-moz-box-sizing: border-box;
text-indent: 0;
}
table[align="left"] {
float: left;
}
table[align="right"] {
float: right;
text-align: start;
}
table[rules]:not([rules="none"]) {
border-collapse: collapse;
}

caption {
display: table-caption;
text-align: center;
-moz-box-sizing: border-box;
}
table[align="center"] > caption {
margin-left: auto;
margin-right: auto;
}
table[align="center"] > caption[align="left"] {
margin-right: 0;
}
table[align="center"] > caption[align="right"] {
margin-left: 0;
}
tr {
display: table-row;
vertical-align: inherit;
}
col {
display: table-column;
}
colgroup {
display: table-column-group;
}
tbody {
display: table-row-group;
vertical-align: middle;
}
thead {
display: table-header-group;
vertical-align: middle;
}
tfoot {
display: table-footer-group;
vertical-align: middle;
}

table > tr {
vertical-align: middle;
}
td {
display: table-cell;
vertical-align: inherit;
text-align: inherit;
padding: 1px;
}
th {
display: table-cell;
vertical-align: inherit;
font-weight: bold;
padding: 1px;
}
tr > form:-moz-is-html, tbody > form:-moz-is-html,
thead > form:-moz-is-html, tfoot > form:-moz-is-html,
table > form:-moz-is-html {

display: none !important;
}

q:before {
content: open-quote;
}
q:after {
content: close-quote;
}
b, strong {
font-weight: bolder;
}
i, cite, em, var, dfn {
font-style: italic;
}
tt, code, kbd, samp {
font-family: -moz-fixed;
}
u, ins {
text-decoration: underline;
}
s, strike, del {
text-decoration: line-through;
}
blink {
text-decoration: blink;
}
big {
font-size: larger;
}
small {
font-size: smaller;
}
sub {
vertical-align: sub;
font-size: smaller;
line-height: normal;
}
sup {
vertical-align: super;
font-size: smaller;
line-height: normal;
}
nobr {
white-space: nowrap;
}

abbr[title], acronym[title] {
border-bottom: dotted 1px;
}

ul, menu, dir {
display: block;
list-style-type: disc;
margin: 1em 0;
-moz-padding-start: 40px;
}
ol {
display: block;
list-style-type: decimal;
margin: 1em 0;
-moz-padding-start: 40px;
}
li {
display: list-item;
}

ul ul, ul ol, ul dir, ul menu, ul dl,
ol ul, ol ol, ol dir, ol menu, ol dl,
dir ul, dir ol, dir dir, dir menu, dir dl,
menu ul, menu ol, menu dir, menu menu, menu dl,
dl ul, dl ol, dl dir, dl menu, dl dl {
margin-top: 0;
margin-bottom: 0;
}

ol ul, ul ul, menu ul, dir ul,
ol menu, ul menu, menu menu, dir menu,
ol dir, ul dir, menu dir, dir dir {
list-style-type: circle;
}

ol ol ul, ol ul ul, ol menu ul, ol dir ul,
ol ol menu, ol ul menu, ol menu menu, ol dir menu,
ol ol dir, ol ul dir, ol menu dir, ol dir dir,
ul ol ul, ul ul ul, ul menu ul, ul dir ul,
ul ol menu, ul ul menu, ul menu menu, ul dir menu,
ul ol dir, ul ul dir, ul menu dir, ul dir dir,
menu ol ul, menu ul ul, menu menu ul, menu dir ul,
menu ol menu, menu ul menu, menu menu menu, menu dir menu,
menu ol dir, menu ul dir, menu menu dir, menu dir dir,
dir ol ul, dir ul ul, dir menu ul, dir dir ul,
dir ol menu, dir ul menu, dir menu menu, dir dir menu,
dir ol dir, dir ul dir, dir menu dir, dir dir dir {
list-style-type: square;
}

/* <hr> noshade and color attributes are handled completely by
* the nsHTMLHRElement attribute mapping code
*/
hr {
display: block;
height: 2px;
border: 1px inset;
margin: 0.5em auto 0.5em auto;
color: gray;
-moz-float-edge: margin-box;
-moz-box-sizing: border-box;
}
hr[size="1"] {
border-style: solid none none none;
}
*|*:-moz-any-link img, img[usemap], object[usemap] {
border: 2px solid;
}
img:-moz-broken::before, input:-moz-broken::before,
img:-moz-user-disabled::before, input:-moz-user-disabled::before,
img:-moz-loading::before, input:-moz-loading::before,
applet:-moz-empty-except-children-with-localname(param):-moz-broken::before,
applet:-moz-empty-except-children-with-localname(param):-moz-user-disabled::before {
content: -moz-alt-content !important;
unicode-bidi: embed;
}
object:-moz-broken > *|*, applet:-moz-broken > *|*
object:-moz-user-disabled > *|*, applet:-moz-user-disabled > *|* {

vertical-align: inherit;
}
img:-moz-suppressed, input:-moz-suppressed, object:-moz-suppressed,
embed:-moz-suppressed, applet:-moz-suppressed {

display: none !important;
visibility: hidden !important;
}
img[usemap], object[usemap] {
color: blue;
}
frameset {
display: block ! important;
overflow: -moz-hidden-unscrollable;
position: static ! important;
float: none ! important;
border: none ! important;
}
frame {
border: none ! important;
}
iframe {
border: 2px inset;
}
noframes {
display: none;
}
spacer {
position: static ! important;
float: none ! important;
}
canvas {
-moz-user-select: none;
}

abbr:focus, acronym:focus, address:focus, applet:focus, b:focus,
base:focus, big:focus, blockquote:focus, br:focus, canvas:focus, caption:focus,
center:focus, cite:focus, code:focus, col:focus, colgroup:focus, dd:focus,
del:focus, dfn:focus, dir:focus, div:focus, dl:focus, dt:focus, em:focus,
fieldset:focus, font:focus, form:focus, h1:focus, h2:focus, h3:focus, h4:focus,
h5:focus, h6:focus, hr:focus, i:focus, img:focus, ins:focus,
kbd:focus, label:focus, legend:focus, li:focus, link:focus, menu:focus,
object:focus, ol:focus, p:focus, pre:focus, q:focus, s:focus, samp:focus,
small:focus, span:focus, strike:focus, strong:focus, sub:focus, sup:focus,
table:focus, tbody:focus, td:focus, tfoot:focus, th:focus, thead:focus,
tr:focus, tt:focus, u:focus, ul:focus, var:focus {

outline: 1px dotted;
}

area, base, basefont, head, meta, script, style, title,
noembed, param {
display: none;
}

marquee {
width: -moz-available;
display: inline-block;
vertical-align: text-bottom;
text-align: start;
-moz-binding: url('chrome://xbl-marquee/content/xbl-marquee.xml#marquee-horizontal');
}
marquee[direction="up"], marquee[direction="down"] {
-moz-binding: url('chrome://xbl-marquee/content/xbl-marquee.xml#marquee-vertical');
height: 200px;
}

@media print {
marquee { -moz-binding: none; }

blink {
text-decoration: none;
}
}