.btn-back{background:#003865;border-radius:100%;cursor:pointer;height:40px;left:8px;padding:10px;position:fixed;top:90px;transition:all .3s ease-in-out;width:40px;z-index:999}.btn-back:hover{background:#ffb81c}.btn-back img{height:100%;transition:all .3s ease-in-out;width:100%}.btn-back:hover img{filter:brightness(0) saturate(100%) invert(15%) sepia(60%) saturate(700%) hue-rotate(185deg) brightness(90%)}