body{font-family:Arial,sans-serif;background-color:#f4f4f4;display:flex;justify-content:center;padding:20px}.container{background:#fff;padding:20px;border-radius:8px;box-shadow:0 2px 4px #0000001a;width:100%;max-width:400px}h1{text-align:center;color:#333}form{display:flex;gap:10px;margin-bottom:20px}input{flex:1;padding:8px;border:1px solid #ddd;border-radius:4px}button{padding:8px 16px;background-color:#007bff;color:#fff;border:none;border-radius:4px;cursor:pointer}button:hover{background-color:#0056b3}ul{list-style:none;padding:0}li{display:flex;justify-content:space-between;align-items:center;padding:10px;border-bottom:1px solid #eee}li.completed span{text-decoration:line-through;color:#888}li span{cursor:pointer;flex:1}li button{background-color:#dc3545;padding:4px 8px;font-size:12px}li button:hover{background-color:#c82333}