js控制元素的显示与隐藏
.inner1{width:600px; height:200px; margin:0 auto; background-color:rgb(56,95,147);}
.inner2{width:0; height:0; margin:0 auto; border-left:300px solid rgb(56,95,147); border-top:100px solid rgb(56,95,147); border-right:300px solid transparent; border-bottom:100px solid transparent;}
