.btn-fill-animation:before{content:"";position:absolute;top:var(--y);left:var(--x);transform:translate(-50%,-50%);width:0;height:0;background:radial-gradient(circle,#ff7f32 0,#ff2800 100%);border-radius:100%;transition:width .75s,height .75s}.btn-fill-animation:hover:before{width:1500px;height:1500px}