css整理 background-size优化

font-size:12px;
line-height:22px;
font-family:Arial,Helvetica,sans-serif;

/*优化*/
font:12px/22px Arial,Helvetica,sans-serif;


background-color:#eee;
background-image:url(background.gif);
background-repeat:no-repeat;
background-attachment:fixed;
background-position:0 0;
background-size:50px 50px;
/*优化  background-size*/
background:#f00 url(background.gif) no-repeat fixed 0 0/50px 50px;

background:#f00 url(background.gif) no-repeat fixed 0 0/cover; 安卓低版本不兼容

/*针对低版本浏览器none无效*/ border:none;border:09; /*激活虚线问题*/ a:active,a:focus{outline:none; star:expression(this.onFocus=this.blur());}