/* ========== 1. CSS Variables ========== */
    :root {
        --primary: #0a4d8c;
        --primary-dark: #042449;
        --primary-light: #e8f2fb;
        --secondary: #1e3a5f;
        --accent: #2563eb;
        --accent-light: #60a5fa;
        --gold: #d4af37;
        --white: #ffffff;
        --gray-50: #f8fafc;
        --gray-100: #f1f5f9;
        --gray-200: #e2e8f0;
        --gray-300: #cbd5e1;
        --gray-600: #475569;
        --gray-700: #334155;
        --gray-800: #1e293b;
        --text: #0f172a;
        --text-light: #64748b;
        --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
        --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
        --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
        --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
        --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
        --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
        --gradient-primary: linear-gradient(135deg, #0a4d8c 0%, #1e3a5f 100%);
        --gradient-accent: linear-gradient(135deg, #2563eb 0%, #60a5fa 100%);
        --gradient-gold: linear-gradient(135deg, #d4af37 0%, #f59e0b 100%);
    }

    * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
    }

    body {
        background: linear-gradient(180deg, var(--gray-50) 0%, var(--gray-100) 100%);
        font-family: 'Prompt', 'Inter', system-ui, -apple-system, sans-serif;
        overflow-x: hidden;
    }

    /* ========== 2. Background Orbs ========== */
    .bg-orb {
        position: fixed;
        border-radius: 50%;
        filter: blur(80px);
        opacity: 0.3;
        z-index: 0;
        pointer-events: none;
    }

    .bg-orb-1 {
        width: 500px;
        height: 500px;
        background: radial-gradient(circle, var(--accent-light), transparent);
        top: -200px;
        right: -100px;
    }

    .bg-orb-2 {
        width: 600px;
        height: 600px;
        background: radial-gradient(circle, var(--primary-light), transparent);
        bottom: -200px;
        left: -150px;
    }

    .bg-orb-3 {
        width: 400px;
        height: 400px;
        background: radial-gradient(circle, rgba(212, 175, 55, 0.2), transparent);
        top: 40%;
        right: 10%;
    }

    /* ========== 3. Hero Section ========== */
    .hero-section {
        position: relative;
        background: var(--gradient-primary);
        padding: 60px 0 80px;
        overflow: hidden;
        z-index: 1;
    }

    .hero-section::after {
        content: '';
        position: absolute;
        bottom: -2px;
        left: 0;
        right: 0;
        height: 80px;
        background: linear-gradient(to top, var(--gray-50), transparent);
        z-index: 2;
    }

    .hero-floating {
        position: absolute;
        width: 300px;
        height: 300px;
        background: radial-gradient(circle, rgba(255,255,255,0.08), transparent);
        border-radius: 50%;
        top: -150px;
        left: -100px;
        animation: float 20s infinite ease-in-out;
    }

    .hero-floating-2 {
        position: absolute;
        width: 200px;
        height: 200px;
        background: radial-gradient(circle, rgba(255,255,255,0.05), transparent);
        border-radius: 50%;
        bottom: -80px;
        right: 10%;
        animation: float 15s infinite ease-in-out reverse;
    }

    @keyframes float {
        0%, 100% { transform: translate(0, 0) rotate(0deg); }
        50% { transform: translate(30px, 20px) rotate(5deg); }
    }

    @keyframes fadeInUp {
        from {
            opacity: 0;
            transform: translateY(25px);
        }
        to {
            opacity: 1;
            transform: translateY(0);
        }
    }

    .hero-content {
        position: relative;
        z-index: 3;
        text-align: center;
        max-width: 800px;
        margin: 0 auto;
    }

    .hero-badge {
        display: inline-flex;
        align-items: center;
        gap: 8px;
        background: rgba(255,255,255,0.12);
        backdrop-filter: blur(10px);
        border: 1px solid rgba(255,255,255,0.2);
        color: var(--accent-light);
        padding: 6px 20px;
        border-radius: 100px;
        font-size: 0.8rem;
        font-weight: 500;
        letter-spacing: 0.5px;
        margin-bottom: 24px;
    }

    .hero-title {
        font-size: 2.5rem;
        font-weight: 700;
        color: var(--white);
        margin-bottom: 16px;
        letter-spacing: -0.02em;
        opacity: 0;
        animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1) forwards;
    }

    .hero-title span {
        background: linear-gradient(135deg, var(--accent-light), var(--gold));
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        background-clip: text;
    }

    .hero-subtitle {
        font-size: 1rem;
        color: rgba(255,255,255,0.85);
        max-width: 650px;
        margin: 0 auto;
        line-height: 1.6;
        opacity: 0;
        animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1) 0.3s forwards;
    }

    /* ========== 4. Certificate Section ========== */
    .cert-section {
        position: relative;
        padding: 60px 0 80px;
        z-index: 2;
    }

    .section-header {
        text-align: center;
        margin-bottom: 40px;
    }

    .section-tag {
        display: inline-block;
        background: linear-gradient(135deg, var(--primary-light), rgba(37, 99, 235, 0.1));
        color: var(--primary);
        padding: 6px 16px;
        border-radius: 100px;
        font-size: 0.8rem;
        font-weight: 600;
        text-transform: uppercase;
        letter-spacing: 1px;
        margin-bottom: 12px;
    }

    .section-title {
        font-size: 2rem;
        font-weight: 700;
        color: var(--text);
        margin-bottom: 16px;
        opacity: 0;
        animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1) 0.5s forwards;
    }

    .section-divider {
        width: 80px;
        height: 4px;
        background: var(--gradient-accent);
        margin: 0 auto;
        border-radius: 4px;
    }

    /* Filter Buttons */
    .filter-buttons {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 12px;
        margin-bottom: 40px;
    }

    .filter-btn {
        padding: 10px 24px;
        background: var(--white);
        border: 2px solid var(--primary);
        color: var(--primary);
        border-radius: 60px;
        font-weight: 600;
        font-size: 0.85rem;
        cursor: pointer;
        transition: var(--transition);
        font-family: 'Prompt', sans-serif;
        text-decoration: none;
        display: inline-block;
    }

    .filter-btn:hover {
        background: var(--primary);
        color: var(--white);
        transform: translateY(-2px);
        text-decoration: none;
    }

    .filter-btn.active {
        background: var(--primary);
        color: var(--white);
        box-shadow: var(--shadow-md);
    }

    /* Certificate Cards */
    .cert-grid {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
        gap: 30px;
    }

    .cert-card {
        background: var(--white);
        border-radius: 24px;
        overflow: hidden;
        transition: var(--transition);
        border: 1px solid var(--gray-200);
        box-shadow: var(--shadow-md);
        cursor: pointer;
        display: flex;
        flex-direction: column;
    }

    .cert-card:hover {
        transform: translateY(-8px);
        box-shadow: var(--shadow-2xl);
    }

    .cert-image-wrapper {
        position: relative;
        overflow: hidden;
        background: linear-gradient(135deg, var(--gray-50), var(--white));
        padding: 20px;
        text-align: center;
        cursor: pointer;
        flex-shrink: 0;
    }

    .cert-image {
        width: 100%;
        height: 180px;
        object-fit: contain;
        transition: var(--transition);
    }

    .cert-card:hover .cert-image {
        transform: scale(1.03);
    }

    .zoom-icon-cert {
        position: absolute;
        bottom: 15px;
        right: 15px;
        background: rgba(10, 77, 140, 0.8);
        width: 36px;
        height: 36px;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        color: var(--white);
        font-size: 18px;
        opacity: 0;
        transition: var(--transition);
        backdrop-filter: blur(4px);
    }

    .cert-card:hover .zoom-icon-cert {
        opacity: 1;
    }

    .cert-body {
        padding: 20px 24px 24px;
        text-align: center;
        display: flex;
        flex-direction: column;
        flex: 1;
    }

    .cert-title {
        font-size: 1.1rem;
        font-weight: 700;
        color: var(--primary);
        margin-bottom: 8px;
    }

    .cert-desc {
        font-size: 0.85rem;
        color: var(--text-light);
        margin-bottom: 16px;
        line-height: 1.5;
        flex: 1;
    }

    .btn-download {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: 10px;
        width: 100%;
        padding: 12px 20px;
        background: var(--gradient-primary);
        color: var(--white);
        border: none;
        border-radius: 60px;
        font-weight: 600;
        font-size: 0.9rem;
        text-decoration: none;
        transition: var(--transition);
        cursor: pointer;
        text-align: center;
        min-height: 48px;
        margin-top: auto;
    }

    .btn-download i {
        font-size: 1rem;
        flex-shrink: 0;
    }

    .btn-download span {
        flex: 1;
        text-align: center;
    }

    .btn-download:hover {
        transform: translateY(-2px);
        box-shadow: var(--shadow-lg);
        text-decoration: none;
        color: var(--white);
    }

    .cert-card.hidden {
        display: none;
    }

    /* Lightbox Modal */
    .lightbox-modal {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0, 0, 0, 0.95);
        z-index: 1000;
        cursor: pointer;
        opacity: 0;
        transition: opacity 0.3s ease;
    }

    .lightbox-modal.active {
        display: flex !important;
        align-items: center;
        justify-content: center;
        opacity: 1;
    }

    .lightbox-content {
        max-width: 100%;
        max-height: 100%;
        position: relative;
        animation: zoomIn 0.3s ease;
        display: flex;
        align-items: center;
        justify-content: center;
    }

    @keyframes zoomIn {
        from {
            transform: scale(0.8);
            opacity: 0;
        }
        to {
            transform: scale(1);
            opacity: 1;
        }
    }

    .lightbox-image {
        max-width: 95vw;
        max-height: 95vh;
        width: auto;
        height: auto;
        object-fit: contain;
        border-radius: 12px;
        box-shadow: var(--shadow-2xl);
    }

    .lightbox-close {
        position: absolute;
        top: 20px;
        right: 30px;
        color: var(--white);
        font-size: 40px;
        font-weight: bold;
        cursor: pointer;
        transition: var(--transition);
        z-index: 1001;
        width: 50px;
        height: 50px;
        display: flex;
        align-items: center;
        justify-content: center;
        border-radius: 50%;
        background: rgba(255,255,255,0.1);
    }

    .lightbox-close:hover {
        background: rgba(255,255,255,0.2);
        transform: scale(1.1);
    }

    /* ========== 5. Responsive ========== */
    @media (max-width: 991px) {
        .hero-title { font-size: 2rem; }
        .hero-section { padding: 50px 0 70px; }
        .section-title { font-size: 1.5rem; }
        .cert-grid { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }
        .cert-image { height: 160px; }
    }

    @media (max-width: 767px) {
        .hero-section { padding: 40px 0 60px; }
        .hero-title { font-size: 1.4rem; }
        .hero-badge { font-size: 0.7rem; padding: 4px 14px; }
        .hero-subtitle { font-size: 0.85rem; }
        .cert-section { padding: 40px 0 60px; }
        .filter-buttons { gap: 8px; }
        .filter-btn { padding: 6px 16px; font-size: 0.75rem; }
        .cert-grid { gap: 20px; }
        .cert-image { height: 140px; }
        .cert-body { padding: 16px 20px 20px; }
        .cert-title { font-size: 1rem; }
        .cert-desc { font-size: 0.8rem; }
        .btn-download { padding: 10px 16px; font-size: 0.8rem; min-height: 42px; }
        .zoom-icon-cert { width: 30px; height: 30px; font-size: 14px; bottom: 10px; right: 10px; }
        .lightbox-close { font-size: 30px; width: 40px; height: 40px; top: 15px; right: 20px; }
        .lightbox-image { max-width: 98vw; max-height: 90vh; }
    }

    @media (max-width: 480px) {
        .hero-title { font-size: 1.2rem; }
        .cert-grid { grid-template-columns: 1fr; }
        .cert-image { height: 120px; }
        .zoom-icon-cert { width: 28px; height: 28px; font-size: 12px; }
        .btn-download { padding: 8px 14px; font-size: 0.75rem; min-height: 38px; }
    }