:root {
    --primary: #FFD700;
    --primary-dark: #FFC500;
    --dark: #1a1a1a;
    --text: #333;
    --text-light: #666;
    --border: #e0e0e0;
    --white: #ffffff;
}

/* ========== HERO SECTION ========== */
.ai_hub .hero {
    background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 100%);
    color: var(--white);
    padding: 4rem 2rem;
    text-align: center;
}

.ai_hub .hero-content {
    max-width: 900px;
    margin: 0 auto;
}

.ai_hub .hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.ai_hub .hero-subtitle {
    font-size: 1.2rem;
    color: #ccc;
    margin-bottom: 2rem;
}

.ai_hub .hero-highlight {
    display: inline-block;
    background: var(--primary);
    color: var(--dark);
    padding: 0.5rem 1rem;
    border-radius: 4px;
    font-weight: bold;
    margin-bottom: 2rem;
}

.ai_hub .cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.ai_hub .btn {
    padding: 0.8rem 2rem;
    border: none;
    border-radius: 4px;
    font-size: 1rem;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.3s;
    font-weight: 600;
}

.ai_hub .btn-primary {
    background: var(--primary);
    color: var(--dark);
}

.ai_hub .btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

.ai_hub .btn-secondary {
    background: transparent;
    color: var(--white);
    border: 2px solid var(--white);
}

.ai_hub .btn-secondary:hover {
    background: var(--white);
    color: var(--dark);
}

/* ========== PROBLEM SECTION ========== */
.ai_hub .section {
    padding: 4rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.ai_hub .section-title {
    font-size: 2rem;
    margin-bottom: 1rem;
    text-align: center;
    color: var(--dark);
}

.ai_hub .section-subtitle {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.ai_hub .problems-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.ai_hub .problem-card {
    background: #f9f9f9;
    padding: 2rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary);
}

.ai_hub .problem-card h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.ai_hub .problem-card p {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* ========== SERVICES SECTION ========== */
.ai_hub .services-section {
    background: #f5f5f5;
}

.ai_hub .services-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.ai_hub .service-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    border: 2px solid transparent;
    transition: all 0.3s;
}

.ai_hub .service-card:hover {
    border-color: var(--primary);
    box-shadow: 0 8px 16px rgba(0,0,0,0.1);
}

.ai_hub .service-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

/* ========== FORM VALIDATION STYLES ========== */
.ai_hub .form-group {
    margin-bottom: 1rem;
}

.ai_hub .form-group input,
.ai_hub .form-group select,
.ai_hub .form-group textarea {
    width: 100%;
    padding: 0.8rem;
    border: 2px solid #ddd;
    border-radius: 4px;
    font-family: inherit;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.ai_hub .form-group input:focus,
.ai_hub .form-group select:focus,
.ai_hub .form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
    background-color: #fffbf0;
    box-shadow: 0 0 8px rgba(255, 215, 0, 0.3);
}

/* ========== ERROR STYLES ========== */
.ai_hub .form-group.error input,
.ai_hub .form-group.error select,
.ai_hub .form-group.error textarea {
    border-color: #dc3545 !important;
    border-width: 2px;
    background-color: #fff5f5;
    box-shadow: 0 0 12px rgba(220, 53, 69, 0.4),
                inset 0 0 4px rgba(220, 53, 69, 0.1);
    animation: errorShake 0.3s ease;
}

/* Animation: Rung lên khi error */
@keyframes errorShake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

/* Thêm icon error bên phải input */
.ai_hub .form-group.error::after {
    content: "⚠";
    position: absolute;
    right: 15px;
    top: 30%;
    transform: translateY(-50%);
    color: #dc3545;
    font-size: 1.2rem;
    font-weight: bold;
}

.ai_hub .error-message {
    display: none;
    color: #dc3545;
    font-size: 0.85rem;
    margin-top: 0.3rem;
    font-weight: 600;
    padding: 0.4rem 0.5rem;
    background-color: #ffe5e5;
    border-radius: 3px;
    border-left: 3px solid #dc3545;
}

.ai_hub .form-group.error .error-message {
    display: block;
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.ai_hub .success-message {
    display: none;
    background: #d4edda;
    color: #155724;
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1rem;
    text-align: center;
    font-weight: 600;
}

.ai_hub .success-message.show {
    display: block;
}

.ai_hub .service-card h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--dark);
}

.ai_hub .service-card p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.ai_hub .service-features {
    list-style: none;
    margin-bottom: 1.5rem;
}

.ai_hub .service-features li {
    padding: 0.4rem 0;
    color: var(--text-light);
    font-size: 0.9rem;
}

.ai_hub .service-features li:before {
    content: "✓ ";
    color: var(--primary);
    font-weight: bold;
    margin-right: 0.5rem;
}

/* ========== CASE STUDY ========== */
.ai_hub .case-study {
    background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 100%);
    color: var(--white);
}

.ai_hub .case-study-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.ai_hub .case-study-image {
    background: rgba(255, 215, 0, 0.1);
    height: 300px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
}

.ai_hub .case-study h2 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
}

.ai_hub .case-study-brand {
    color: var(--primary);
    font-weight: bold;
    font-size: 1.1rem;
    margin-bottom: 1rem;
}

.ai_hub .metrics {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.ai_hub .metric {
    background: rgba(255, 215, 0, 0.1);
    padding: 1.5rem;
    border-radius: 8px;
    text-align: center;
}

.ai_hub .metric-value {
    font-size: 2rem;
    font-weight: bold;
    color: var(--primary);
}

.ai_hub .metric-label {
    font-size: 0.85rem;
    color: #ccc;
    margin-top: 0.5rem;
}

.ai_hub .case-study-text {
    color: #ccc;
    line-height: 1.8;
}

@media (max-width: 768px) {
    .ai_hub .case-study-content {
        grid-template-columns: 1fr;
    }
}

/* ========== PRICING SECTION ========== */
.ai_hub .pricing-section {
    background: var(--white);
}

.ai_hub .pricing-tabs {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
}

.ai_hub .tab-btn {
    padding: 0.6rem 1.5rem;
    border: 2px solid var(--border);
    background: var(--white);
    cursor: pointer;
    border-radius: 4px;
    font-weight: 600;
    transition: all 0.3s;
}

.ai_hub .tab-btn.active {
    background: var(--primary);
    color: var(--dark);
    border-color: var(--primary);
}

.ai_hub .pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.ai_hub .pricing-card {
    background: var(--white);
    border: 2px solid var(--border);
    border-radius: 8px;
    padding: 2rem;
    transition: all 0.3s;
}

.ai_hub .pricing-card.featured {
    border-color: var(--primary);
    box-shadow: 0 8px 24px rgba(255, 215, 0, 0.2);
    transform: scale(1.05);
}

.ai_hub .badge {
    display: inline-block;
    background: var(--primary);
    color: var(--dark);
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: bold;
    margin-bottom: 1rem;
}

.ai_hub .pricing-card h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.ai_hub .pricing-card p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
}

.ai_hub .price {
    font-size: 2rem;
    font-weight: bold;
    color: var(--primary);
    margin: 1.5rem 0;
}

.ai_hub .price-note {
    font-size: 0.8rem;
    color: var(--text-light);
    margin-bottom: 1.5rem;
}

.ai_hub .pricing-features {
    list-style: none;
    margin-bottom: 2rem;
}

.ai_hub .pricing-features li {
    padding: 0.5rem 0;
    color: var(--text-light);
    font-size: 0.9rem;
    border-bottom: 1px solid var(--border);
}

.ai_hub .pricing-features li:last-child {
    border-bottom: none;
}

.ai_hub .pricing-features li:before {
    content: "✓ ";
    color: var(--primary);
    font-weight: bold;
    margin-right: 0.5rem;
}

/* ========== HOW IT WORKS ========== */
.ai_hub .how-it-works {
    background: #f5f5f5;
}

.ai_hub .steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.ai_hub .step {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    text-align: center;
}

.ai_hub .step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--primary);
    color: var(--dark);
    border-radius: 50%;
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 1rem;
}

.ai_hub .step h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
}

.ai_hub .step p {
    color: var(--text-light);
    font-size: 0.9rem;
}

/* ========== FAQ SECTION ========== */
.ai_hub .faq-section {
    background: var(--white);
}

.ai_hub .faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.ai_hub .faq-item {
    background: #f9f9f9;
    padding: 1.5rem;
    margin-bottom: 1rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary);
}

.ai_hub .faq-question {
    font-weight: 600;
    color: var(--dark);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
}

.ai_hub .faq-toggle {
    font-size: 1.2rem;
    transition: transform 0.3s;
}

.ai_hub .faq-item.active .faq-toggle {
    transform: rotate(180deg);
}

.ai_hub .faq-answer {
    display: none;
    margin-top: 1rem;
    color: var(--text-light);
    line-height: 1.8;
}

.ai_hub .faq-item.active .faq-answer {
    display: block;
}

/* ========== CTA SECTION ========== */
.ai_hub .cta-final {
    background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 100%);
    color: var(--white);
    text-align: center;
    padding: 3rem 2rem;
}

.ai_hub .cta-final h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.ai_hub .cta-final p {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    color: #ccc;
}

/* ========== FOOTER ========== */
.ai_hub footer {
    background: var(--dark);
    color: var(--white);
    padding: 2rem;
    text-align: center;
    border-top: 2px solid var(--primary);
}

/* ========== RESPONSIVE ========== */
@media (max-width: 768px) {
    .ai_hub .cta-final {
        padding: .25rem .15rem;
    }

    .ai_hub .hero h1 {
        font-size: 1.8rem;
    }

    .ai_hub .section-title {
        font-size: 1.5rem;
    }

    .ai_hub .cta-buttons {
        flex-direction: column;
    }

    .ai_hub .btn {
        width: 100%;
    }

    .ai_hub nav {
        display: none;
    }

    .ai_hub .pricing-card.featured {
        transform: scale(1);
    }
}

/* ========== UTILITY CLASSES ========== */
.ai_hub .container {
    max-width: 1200px;
    margin: 0 auto;
}

.ai_hub .mt-3 {
    margin-top: 2rem;
}