用border做一个移动端常见的返回按钮

.hs1{
        float: left;
        .mt(.25rem);
        .ml(.12rem);
        width: .3rem;
        height: .3rem;
        border-top: 2px solid #fff;  //关键
        border-left: 2px solid #fff;  //关键
        color: #fff;
    }

.hs1{
        float: left;
        .mt(.25rem);
        .ml(.12rem);
        width: .3rem;
        height: .3rem;
        border-top: 2px solid #fff;
        border-left: 2px solid #fff;
        color: #fff;
        -webkit-transform: rotateZ(-45deg);      
        -moz-transform: rotateZ(-45deg);
        -ms-transform: rotateZ(-45deg);
        -o-transform: rotateZ(-45deg);    //上面均是兼容写法
        transform: rotateZ(-45deg);  
    }