*{margin:0;padding:0;box-sizing:border-box}body{font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;background-color:#f5f5f5;color:#333;line-height:1.6}.app{min-height:100vh;padding:20px 0}.container{max-width:600px;margin:0 auto;background-color:#fff;border-radius:10px;box-shadow:0 0 20px #0000001a;padding:30px}h1{text-align:center;color:#2c3e50;margin-bottom:30px;font-size:2.5rem}.task-form{display:flex;gap:10px;margin-bottom:30px}.task-input{flex:1;padding:12px 15px;border:2px solid #ddd;border-radius:5px;font-size:1rem;outline:none;transition:border-color .3s}.task-input:focus{border-color:#3498db}.add-button{padding:12px 20px;background-color:#3498db;color:#fff;border:none;border-radius:5px;cursor:pointer;font-size:1rem;transition:background-color .3s}.add-button:hover{background-color:#2980b9}.task-list{margin-top:20px}.empty-message{text-align:center;color:#7f8c8d;font-style:italic;padding:20px}.task-item{display:flex;align-items:center;gap:10px;padding:15px;border:1px solid #eee;border-radius:5px;margin-bottom:10px;transition:all .3s;background-color:#fafafa}.task-item:hover{box-shadow:0 2px 5px #0000000d}.task-item.completed{background-color:#e8f5e9;opacity:.8}.task-checkbox{width:18px;height:18px;cursor:pointer}.task-text{flex:1;font-size:1.1rem}.task-item.completed .task-text{text-decoration:line-through;color:#95a5a6}.delete-button{padding:8px 15px;background-color:#e74c3c;color:#fff;border:none;border-radius:3px;cursor:pointer;font-size:.9rem;transition:background-color .3s}.delete-button:hover{background-color:#c0392b}@media (max-width: 768px){.container{margin:10px;padding:20px}.task-form{flex-direction:column}h1{font-size:2rem}}