body{margin:0;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}code{font-family:source-code-pro,Menlo,Monaco,Consolas,Courier New,monospace}body{font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;background-color:#f4f7f9;margin:0;display:flex;justify-content:center;align-items:center;min-height:100vh}  .app-container{width:100%;max-width:800px;padding:20px}  .todo-container{background-color:#fff;padding:30px;border-radius:12px;box-shadow:0 4px 12px #0000001a}  h1{text-align:center;color:#333;margin-bottom:25px}  .task-form{display:flex;gap:10px;margin-bottom:25px}  .task-form input{flex-grow:1;padding:12px;border:1px solid #ddd;border-radius:8px;font-size:16px}  .task-form input:focus{outline:none;border-color:#007bff}  .task-form button{padding:12px 20px;background-color:#007bff;color:#fff;border:none;border-radius:8px;cursor:pointer;font-size:16px;transition:background-color .2s}  .task-form button:hover{background-color:#0056b3}  .task-list{list-style:none;padding:0;margin:0}  .task-list li{display:flex;justify-content:space-between;align-items:center;padding:15px;border-bottom:1px solid #eee;gap:15px}  .task-list li:last-child{border-bottom:none}  .task-list li span{cursor:pointer;flex-grow:1}  .task-list li.completed span{text-decoration:line-through;color:#999}  .task-list li button{background-color:#dc3545;color:#fff;border:none;border-radius:6px;padding:8px 12px;cursor:pointer;margin-left:10px;transition:background-color .2s}  .task-list li button:hover{background-color:#c82333}