总结链接
http://www.haorooms.com/post/css3_bg_multi
http://www.haorooms.com/post/CSS_selections
html5 input:file上传类型讲解
http://www.haorooms.com/post/input_file_leixing
div 垂直居中的方法
http://www.haorooms.com/post/css_div_juzhong
css3 :before和 :after 用法
http://blog.csdn.net/qq_30486009/article/details/51500390
原文：http://www.cnblogs.com/xvxv/p/6402396.html