为了那个原因

• 您可以扫描用户代理并找出哪个浏览器及其版本。包括适用于特定于操作系统样式的操作系统
• 您可以为特定的浏览器使用各种CSS技巧
• 或脚本或插件来识别浏览器并将各种类应用于元素

使用PHP

然后根据检测到的浏览器创建动态CSS文件

这是CSS骇客清单

/***** Selector Hacks ******/

/* IE6 and below */
* html #uno  { color: red }

/* IE7 */
*:first-child+html #dos { color: red }

/* IE7, FF, Saf, Opera  */
html>body #tres { color: red }

/* IE8, FF, Saf, Opera (Everything but IE 6,7) */
html>/**/body #cuatro { color: red }

/* Opera 9.27 and below, safari 2 */
html:first-child #cinco { color: red }

/* Safari 2-3 */
html[xmlns*=""] body:last-child #seis { color: red }

/* safari 3+, chrome 1+, opera9+, ff 3.5+ */
body:nth-of-type(1) #siete { color: red }

/* safari 3+, chrome 1+, opera9+, ff 3.5+ */
body:first-of-type #ocho {  color: red }

/* saf3+, chrome1+ */
@media screen and (-webkit-min-device-pixel-ratio:0) {
 #diez  { color: red  }
}

/* iPhone / mobile webkit */
@media screen and (max-device-width: 480px) {
 #veintiseis { color: red  }
}


/* Safari 2 - 3.1 */
html[xmlns*=""]:root #trece  { color: red  }

/* Safari 2 - 3.1, Opera 9.25 */
*|html[xmlns*=""] #catorce { color: red  }

/* Everything but IE6-8 */
:root *> #quince { color: red  }

/* IE7 */
*+html #dieciocho {  color: red }

/* Firefox only. 1+ */
#veinticuatro,  x:-moz-any-link  { color: red }

/* Firefox 3.0+ */
#veinticinco,  x:-moz-any-link, x:default  { color: red  }



/***** Attribute Hacks ******/

/* IE6 */
#once { _color: blue }

/* IE6, IE7 */
#doce { *color: blue; /* or #color: blue */ }

/* Everything but IE6 */
#diecisiete { color/**/: blue }

/* IE6, IE7, IE8 */
#diecinueve { color: blue\9; }

/* IE7, IE8 */
#veinte { color/*\**/: blue\9; }

/* IE6, IE7 -- acts as an !important */
#veintesiete { color: blue !ie; } /* string after ! can be anything */