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css引入方式

方式一：在head里用link标签(推荐使用)
     方式二：在head里用style标签方式三：内联，在标签上用style
     
方式四：@import@import url("xxx.css");link和@import的区别：1.兼容性：@import在IE5+支持，link全部支持2.DOM样式操作：link（可被js改变），@import（不可被js改变）3.加载顺序：@import必须放在最顶部，和link混用时破坏并行加载，link阻断@import，多个@import不同于预期加载顺序

 Hacks

转自：

IE选择器 Hack

/* IE 6 and below */* html .selector  {} .suckyie6.selector {} /* .suckyie6 can be any unused class *//* IE 7 and below */.selector, {}/* IE 7 */*:first-child+html .selector {} .selector, x:-IE7 {} *+html .selector {}/* Everything but IE 6 */html > body .selector {}/* Everything but IE 6/7 */html > /**/ body .selector {}head ~ /* */ body .selector {}/* Everything but IE 6/7/8 */:root *> .selector {} body:last-child .selector {} body:nth-of-type(1) .selector {} body:first-of-type .selector {}

IE属性/值 Hack

/* IE 6 */.selector {
    _color: blue; } .selector {
    -color: blue; }/* IE 6/7 - acts as an !important */.selector {
    color: blue !ie; } /* string after ! can be anything *//* IE 6/7 - any combination of these characters:  ! $ & * ( ) = % + @ , . / ` [ ] # ~ ? : < > | */.selector {
    !color: blue; } .selector {
    $color: blue; } .selector {
    &color: blue; } .selector {
    *color: blue; } /* ... *//* IE 8/9 */.selector {
    color: blue\0/; } /* must go at the END of all rules *//* IE 8/9 */.selector {
    color: blue\0/; } /* must go at the END of all rules *//* IE 9/10 */.selector:nth-of-type(1n) {
    color: blue\9; }/* IE 6/7/8/9/10 */.selector {
    color: blue\9; } .selector {
    color/*\**/: blue\9; }/* Everything but IE 6 */.selector {
    color/**/: blue; }

IE Media Query Hack

/* IE 6/7 */@media screen\9 {}/* IE 8 */@media \0screen {}/* IE 9/10, Firefox 3.5+, Opera */@media screen and (min-resolution: +72dpi) {}/* IE 10+ */@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {}/* IE 6/7/8 */@media \0screen\,screen\9 {}/* IE 8/9/10 & Opera */@media screen\0 {}/* IE 9/10 */@media screen and (min-width:0\0) {}/* Everything but IE 6/7/8 */@media screen and (min-width: 400px) {}

IE Javascript Hack

/* IE 6 */(checkIE = document.createElement("b")).innerHTML = "
     "; var isIE = checkIE.getElementsByTagName("i").length == 1;/* IE 7 */(checkIE = document.createElement("b")).innerHTML = "
     "; var isIE = checkIE.getElementsByTagName("i").length == 1;navigator.appVersion.indexOf("MSIE 7.")!=-1/* IE <= 8 */var isIE = '\v'=='v';/* IE 8 */(checkIE = document.createElement("b")).innerHTML = "
     "; var isIE = checkIE.getElementsByTagName("i").length == 1;/* IE 9 */(checkIE = document.createElement("b")).innerHTML = "
     "; var isIE = checkIE.getElementsByTagName("i").length == 1;/* IE 10 */var isIE = eval("/*@cc_on!@*/false") && document.documentMode === 10;/* IE 10 */var isIE = document.body.style.msTouchAction != undefined;

Firefox 浏览器

选择器Hack/* Firefox 1.5 */body:empty .selector {}/* Firefox 2+ */.selector, x:-moz-any-link {}/* Firefox 3+ */.selector, x:-moz-any-link; x:default {}/* Firefox 3.5+ */body:not(:-moz-handler-blocked) .selector {}媒体查询 Hack/* Firefox 3.5+, IE 9/10, Opera */@media screen and (min-resolution: +72dpi) {}/* Firefox 3.6+ */@media screen and (-moz-images-in-menus:0) {}/* Firefox 4+ */@media screen and (min--moz-device-pixel-ratio:0) {}Javascript Hack/* Firefox */var isFF = !!navigator.userAgent.match(/firefox/i);/* Firefox 2 - 13 */var isFF = Boolean(window.globalStorage);/* Firefox 2/3 */var isFF = /a/[-1]=='a';/* Firefox 3 */var isFF = (function x(){})[-5]=='x';

Chrome浏览器

选择器 Hack/* Chrome 24- and Safari 5- */::made-up-pseudo-element, .selector {}媒体查询 Hack/* Chrome, Safari 3+ */@media screen and (-webkit-min-device-pixel-ratio:0) {}Javascript Hack/* Chrome */var isChrome = Boolean(window.chrome);

Safari浏览器

选择器Hack/* Safari 2/3 */html[xmlns*=""] body:last-child .selector {} html[xmlns*=""]:root .selector  {}/* Safari 2/3.1, Opera 9.25 */*|html[xmlns*=""] .selector {}/* Safari 5- and Chrome 24- */::made-up-pseudo-element, .selector {}媒体查询Hack/* Safari 3+, Chrome */@media screen and (-webkit-min-device-pixel-ratio:0) {}Javascript Hack/* Safari */var isSafari = /a/.__proto__=='//';

Opera浏览器

选择器Hack/* Opera 9.25, Safari 2/3.1 */*|html[xmlns*=""] .selector {}/* Opera 9.27 and below, Safari 2 */html:first-child .selector {}/* Opera 9.5+ */noindex:-o-prefocus, .selector {}媒体查询Hack/* Opera 7 */@media all and (min-width: 0px){}/* Opera 12- */@media all and (-webkit-min-device-pixel-ratio:10000), not all and (-webkit-min-device-pixel-ratio:0) {}/* Opera, Firefox 3.5+, IE 9/10 */@media screen and (min-resolution: +72dpi) {}/* Opera, IE 8/9/10 */@media screen {}Javascript Hack/* Opera 9.64- */var isOpera = /^function \(/.test([].sort);/* Opera 12- */var isOpera = Boolean(window.opera);