body{font-family:Arial,Helvetica,sans-serif;background:#f6f8fa;margin:0;padding:20px}.app{max-width:640px;margin:0 auto;background:#fff;padding:20px;border-radius:8px;box-shadow:0 2px 8px #0000000d}.add-form{display:flex;gap:8px;margin-bottom:16px}.add-form input{flex:1;padding:8px}.add-form button{padding:8px 12px}.todo-list{list-style:none;padding:0;margin:0}.todo-list li{display:flex;justify-content:space-between;align-items:center;padding:8px 0;border-bottom:1px solid #eee}.todo-list li.done span{text-decoration:line-through;color:#888}