*{margin: 0;padding: 0;}
body{padding: 0;position: relative;width: 100%;}
img {border: 0;display: block;width: 100%;}
a{text-decoration: none;-webkit-tap-highlight-color: transparent;}
ul{list-style: none;}
.left{float: left;}
.right{float: right;}
input{-webkit-appearance: none;outline:none;}
.index{position: fixed;left: 0;top: 0;width: 100%;height: 100vh;overflow-y: auto;}

.btns{position: relative;}
.btns .btn{display: none;}
.btns .btn.active{display: block;}
.li{display: none;}
.li.active{display: block;}
.button{
  display: inline-block;
  position: absolute;
  width: 22%;
  height: 8vw;
  left: 15%;
  top: 44%;
}
.b2{left: 39%;}
.b3{left: 63%;}