前端tip

1. background简写 参考地址 http://css.doyoe.com/

   缩写：background:url(test1.jpg) no-repeat scroll 10px 20px/50px 60px content-box padding-box,
   	   url(test1.jpg) no-repeat scroll 10px 20px/70px 90px content-box padding-box,
   	   url(test1.jpg) no-repeat scroll 10px 20px/110px 130px content-box padding-box #aaa;

   拆分：background-image:url(test1.jpg),url(test2.jpg),url(test3.jpg);
   background-repeat:no-repeat,no-repeat,no-repeat;
   background-attachment:scroll,scroll,scroll;
   background-position:10px 20px,10px 20px,10px 20px;
   background-size:50px 60px,70px 90px,110px 130px;
   background-origin:content-box,content-box,content-box;
   background-clip:padding-box,padding-box,padding-box;
   background-color:#aaa;

2. margin-top 失效：inline元素，外边距合并