开始的时候 *{margin:0;padding:0;}，当需要使用边距的时候，就需要还原HTML默认CSS值了。以前一直在找这份 文档，今天偶然在w3上看到了。除了inline和block的定义，主要是要注意body|h1~h6|blockquote|menu|ul|ol|dd等标签的默认样式（margin和font-size）。这个东 西在你需要还原默认值的时候，比较有用。 详见下面的内容：
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}@media print{
h1{page-break-before:always}
h1,h2,h3,
h4,h5,h6{page-break-after:avoid}
ul,ol,dl{page-break-before:avoid}