.btn-slide-down{position:relative;overflow:hidden;z-index:1}.btn-slide-down::after{content:"";position:absolute;top:-100%;left:0;width:100%;height:100%;background:#e60000;z-index:-1;transition:top 0.3s ease}.btn-slide-down:hover::after{top:0}.btn-slide-down:hover{color:#fff!important}