*{font-family:system-ui}.app{min-height:100vh;background:#f7f7f7;color:#222;display:flex;flex-direction:column;align-items:center;padding-top:60px}.dark{background:#111;color:#fff}.theme-btn{position:absolute;top:20px;right:20px;border:none;padding:10px;border-radius:50%;cursor:pointer}.input-box{display:flex;margin:20px 0;width:320px}.input-box input{flex:1;padding:12px;border-radius:20px;border:1px solid #ccc;outline:none}.input-box button{margin-left:10px;width:45px;border-radius:50%;border:none;font-size:20px;cursor:pointer}.list{width:320px}.todo{display:flex;align-items:center;background:#fff;padding:12px;border-radius:12px;margin-bottom:10px}.dark .todo{background:#222}.todo span{margin-left:10px}.done{text-decoration:line-through;opacity:.6}