.Back{position:relative;width:40px;height:40px;background-color:#720000;box-shadow:0 0 20px rgba(114,0,0,.25);cursor:pointer;background-image:url(/images/back.svg);background-size:20px auto;background-repeat:no-repeat;background-position:50%}.Back:hover{background-color:#7f0000}.Back.Back_light{background-color:#ffe2e2;box-shadow:0 0 20px rgba(114,0,0,.15);background-image:url(/images/back-positive.svg)}.Back.Back_light:hover{background-color:#ffefef}.Back.Back_fixed{position:fixed;z-index:100;top:20px;left:20px}