便捷方法:
- padding不影响宽度CSS
-moz-box-sizing: border-box; /*Firefox3.5+*/ -webkit-box-sizing: border-box; /*Safari3.2+*/ -o-box-sizing: border-box; /*Opera9.6*/ -ms-box-sizing: border-box; /*IE8*/ box-sizing: border-box; /*W3C标准(IE9+,Safari5.1+,Chrome10.0+,Opera10.6+都符合box-sizing的w3c标准语法)*/--
===========