body {
            margin: 0;
            padding: 0;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            font-family: 'Arial', sans-serif;
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
        }
        .login-container {
            width: 100%;
            max-width: 400px;
            padding: 20px;
        }
        .login-box {
            background: white;
            padding: 40px;
            border-radius: 10px;
            box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
        }
        .login-box h2 {
            text-align: center;
            color: #333;
            margin-bottom: 30px;
        }
        .user-box {
            margin-bottom: 20px;
            position: relative;
        }
        .user-box input {
            width: 100%;
            padding: 10px;
            border: none;
            border-bottom: 2px solid #667eea;
            background: transparent;
            outline: none;
            font-size: 16px;
            color: #333;
            box-sizing: border-box;
            transition: border-color 0.3s;
        }
        .user-box input:focus {
            border-bottom-color: #764ba2;
        }
        .user-box label {
            position: absolute;
            top: 10px;
            left: 0;
            color: #999;
            font-size: 16px;
            pointer-events: none;
            transition: all 0.3s;
        }
        .user-box input:focus ~ label,
        .user-box input:valid ~ label {
            top: -20px;
            left: 0;
            color: #667eea;
            font-size: 12px;
        }
        .error-message {
            color: #dc3545;
            text-align: center;
            margin-bottom: 20px;
            padding: 10px;
            background: #f8d7da;
            border-radius: 5px;
            display: none;
        }
        .error-message.show {
            display: block;
        }
        .button-group {
            display: flex;
            gap: 10px;
            margin-top: 30px;
        }
        button, .btn-registro {
            flex: 1;
            padding: 12px;
            border: none;
            border-radius: 5px;
            font-size: 16px;
            font-weight: bold;
            cursor: pointer;
            transition: all 0.3s;
            text-decoration: none;
            text-align: center;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        button {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
        }
        button:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
        }
        .btn-registro {
            background: #f0f0f0;
            color: #667eea;
            font-weight: bold;
        }
        .btn-registro:hover {
            background: #e0e0e0;
        }