body{height:100vh;margin:0}canvas{width:100%;height:100%}#overlay{background:#000;flex-direction:column;justify-content:center;align-items:center;transition:all 1s;display:flex;position:fixed;inset:0}.percent{color:#fff;font-size:2rem;transition:all 1s}#start-btn{opacity:0;cursor:pointer;border:none;border-radius:8px;padding:8px 24px;font-size:2rem;transition:all 1s;display:none}.slide-up{transform:translateY(-100vh)}.transparent{opacity:0}#start-btn.appear{opacity:1}.hide{display:none}#start-btn.show{display:block}