body{font-family:Arial,sans-serif;background-color:#f4f4f4;text-align:center;padding:20px}.container{max-width:400px;margin:100px auto auto;background:#fff;padding:20px;border-radius:5px;box-shadow:0 0 10px #0000001a}.input-container{display:flex;gap:10px;margin-bottom:10px}input{flex:1;padding:8px;border:1px solid #ccc;border-radius:4px}button{padding:8px;background:#000;color:#fff;border:none;border-radius:4px;cursor:pointer;margin-left:5px}button:hover{background:#a9a9a9}ul{list-style:none;padding:0}li{display:flex;justify-content:space-between;align-items:center;background:#eee;padding:10px;margin-bottom:5px;border-radius:5px}.completed{text-decoration:line-through;color:gray}