*{margin:0;padding:0;box-sizing:border-box}body{font-family:Arial,sans-serif;background:#fff;color:#000}.wrapper{display:flex;justify-content:center;padding-top:80px}.container{width:600px}h1{font-size:32px;margin-bottom:20px}.add-task{display:flex;align-items:center;gap:10px;margin-bottom:25px}input{flex:1;padding:8px;border:1px solid black;font-size:14px}button{padding:6px 12px;border:1px solid black;background:#fff;cursor:pointer}ul{list-style:none}li{display:flex;justify-content:space-between;align-items:center;padding:10px 0;border-bottom:1px solid black}.btn-group{display:flex;gap:10px}.completed{text-decoration:line-through}