/* ==================== RESET Y BASE ==================== */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 20px;
        }

        /* ==================== CONTENEDOR PRINCIPAL ==================== */
        .login-container {
            background: #ffffff;
            border-radius: 16px;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
            width: 100%;
            max-width: 420px;
            padding: 40px;
            animation: fadeIn 0.5s ease-in-out;
        }

        @keyframes fadeIn {
            from {
                opacity: 0;
                transform: translateY(-20px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        /* ==================== ENCABEZADO ==================== */
        .login-header {
            text-align: center;
            margin-bottom: 35px;
        }

        .login-header h1 {
            color: #2d3748;
            font-size: 28px;
            font-weight: 600;
            margin-bottom: 8px;
        }

        .login-header p {
            color: #718096;
            font-size: 14px;
        }

        /* ==================== MENSAJES DE ERROR ==================== */
        .error-message {
            background-color: #fed7d7;
            color: #c53030;
            padding: 12px 16px;
            border-radius: 8px;
            margin-bottom: 20px;
            font-size: 14px;
            border-left: 4px solid #c53030;
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .error-message::before {
            content: "⚠";
            font-size: 18px;
        }

        .back-link {
            text-align: center;
            margin-top: 15px;
        }

        .back-link a {
            color: #667eea;
            text-decoration: none;
            font-size: 14px;
            transition: color 0.3s ease;
        }

        .back-link a:hover {
            color: #764ba2;
            text-decoration: underline;
        }

        /* ==================== FORMULARIO ==================== */
        .login-form {
            display: flex;
            flex-direction: column;
            gap: 20px;
        }

        .form-group {
            display: flex;
            flex-direction: column;
            gap: 8px;
        }

        .form-group label {
            color: #2d3748;
            font-size: 14px;
            font-weight: 500;
        }

        .form-group input {
            padding: 12px 16px;
            border: 2px solid #e2e8f0;
            border-radius: 8px;
            font-size: 15px;
            transition: all 0.3s ease;
            background-color: #f7fafc;
        }

        .form-group input:focus {
            outline: none;
            border-color: #667eea;
            background-color: #ffffff;
            box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
        }

        /* ==================== BOTÓN ==================== */
        .btn-login {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #ffffff;
            padding: 14px;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: transform 0.2s ease, box-shadow 0.3s ease;
            margin-top: 10px;
        }

        .btn-login:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
        }

        .btn-login:active {
            transform: translateY(0);
        }

        /* ==================== FOOTER ==================== */
        .login-footer {
            text-align: center;
            margin-top: 30px;
            padding-top: 20px;
            border-top: 1px solid #e2e8f0;
        }

        .login-footer p {
            color: #a0aec0;
            font-size: 13px;
        }

        /* ==================== RESPONSIVE ==================== */
        @media (max-width: 480px) {
            .login-container {
                padding: 30px 20px;
            }

            .login-header h1 {
                font-size: 24px;
            }

            .btn-login {
                padding: 12px;
                font-size: 15px;
            }
        }