.app{max-width:800px;margin:0 auto;padding:20px}nav ul{list-style:none;padding:0;display:flex;gap:20px;margin-bottom:30px}nav a{text-decoration:none;color:#333;font-weight:700}nav a:hover{color:#007bff}.form-group{margin-bottom:15px}.form-group label{display:block;margin-bottom:5px}.form-group input{width:100%;padding:8px;box-sizing:border-box}button{padding:8px 16px;background-color:#007bff;color:#fff;border:none;border-radius:4px;cursor:pointer}button:hover{background-color:#0056b3}button:disabled{background-color:#ccc;cursor:not-allowed}.error{color:#dc3545;margin:15px 0}.card{margin-top:30px;padding:20px;border:1px solid #ddd;border-radius:4px}.card-source{margin-top:0;margin-bottom:30px}.button-danger{background-color:#dc3545}.button-danger:hover{background-color:#bd2130}