*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background:#f5f5f5}.app{max-width:600px;margin:0 auto;padding:20px}nav{display:flex;gap:10px;margin-bottom:30px}nav button{padding:10px 20px;border:none;background:#fff;cursor:pointer;border-radius:4px;font-size:16px}nav button.active{background:#0070f3;color:#fff}.todo-page{background:#fff;padding:30px;border-radius:8px;box-shadow:0 2px 8px #0000001a}.todo-form{display:flex;gap:10px;margin-bottom:30px}.todo-form input{flex:1;padding:12px;border:1px solid #ddd;border-radius:4px;font-size:16px}.todo-form button{padding:12px 24px;background:#0070f3;color:#fff;border:none;border-radius:4px;cursor:pointer;font-size:16px}.todo-list{list-style:none}.todo-item{display:flex;align-items:center;gap:12px;padding:12px;border-bottom:1px solid #eee}.todo-item:last-child{border-bottom:none}.todo-item input[type=checkbox]{width:20px;height:20px;cursor:pointer}.todo-item span{flex:1;font-size:16px}.todo-item span.completed{text-decoration:line-through;color:#999}.todo-item button{padding:6px 12px;background:#f44;color:#fff;border:none;border-radius:4px;cursor:pointer;font-size:14px}.upload-page{background:#fff;padding:30px;border-radius:8px;box-shadow:0 2px 8px #0000001a}.upload-form{display:flex;flex-direction:column;gap:20px}.upload-form input[type=file]{padding:12px;border:1px solid #ddd;border-radius:4px;font-size:16px}.upload-form button{padding:12px 24px;background:#0070f3;color:#fff;border:none;border-radius:4px;cursor:pointer;font-size:16px}.message{padding:12px;border-radius:4px;margin-top:20px}.message.success{background:#d4edda;color:#155724}.message.error{background:#f8d7da;color:#721c24}