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

        :root {
            --brand-blue: #005df8;
            --black: #0a0a0a;
            --white: #ffffff;
            --gray-50: #fafafa;
            --gray-100: #f5f5f5;
            --gray-200: #e5e5e5;
            --gray-300: #d4d4d4;
            --gray-600: #525252;
            --gray-900: #171717;
            --success: #10b981;
        }

        body {
            font-family: 'Inter', sans-serif;
            background: var(--white);
            color: var(--black);
            line-height: 1.6;
            -webkit-font-smoothing: antialiased;
        }

        .header {
            position: fixed;
            top: 0;
            width: 100%;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(20px);
            border-bottom: 1px solid var(--gray-200);
            z-index: 1000;
        }

        .nav-container {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 20px 40px;
        }

        .logo {
            font-size: 24px;
            font-weight: 800;
            color: var(--black);
            text-decoration: none;
        }

        .nav-center { display: flex; gap: 40px; }

        .nav-link {
            color: var(--black);
            text-decoration: none;
            font-size: 15px;
            font-weight: 500;
            transition: color 0.2s;
        }

        .nav-link:hover { color: var(--brand-blue); }

        .btn-start {
            background: var(--brand-blue);
            color: var(--white);
            padding: 12px 28px;
            text-decoration: none;
            font-weight: 600;
            font-size: 15px;
        }

        .breadcrumb-section {
            padding: 140px 40px 40px;
            background: var(--gray-50);
        }

        .breadcrumb {
            max-width: 1400px;
            margin: 0 auto;
            display: flex;
            gap: 12px;
            font-size: 14px;
        }

        .breadcrumb a {
            color: var(--gray-600);
            text-decoration: none;
        }

        /* HERO */
        .archive-hero {
            padding: 60px 40px 80px;
            background: var(--gray-50);
        }

        .hero-content {
            max-width: 1400px;
            margin: 0 auto;
        }

        .hero-title {
            font-size: clamp(36px, 4vw, 56px);
            font-weight: 900;
            line-height: 1.1;
            letter-spacing: -2px;
            margin-bottom: 16px;
        }

        .hero-desc {
            font-size: 18px;
            color: var(--gray-600);
            margin-bottom: 32px;
        }

        /* SEARCH BAR */
        .search-container {
            max-width: 700px;
            position: relative;
        }

        .search-input {
            width: 100%;
            padding: 18px 24px 18px 56px;
            border: 2px solid var(--gray-200);
            font-size: 16px;
            background: var(--white);
            outline: none;
            transition: all 0.3s;
        }

        .search-input:focus {
            border-color: var(--brand-blue);
        }

        .search-icon {
            position: absolute;
            left: 20px;
            top: 50%;
            transform: translateY(-50%);
            color: var(--gray-600);
            font-size: 18px;
        }

        /* STATS BAR */
        .stats-bar {
            display: flex;
            gap: 40px;
            margin-top: 32px;
            flex-wrap: wrap;
        }

        .stat-box {
            display: flex;
            align-items: center;
            gap: 12px;
        }

        .stat-icon {
            width: 48px;
            height: 48px;
            background: var(--brand-blue);
            color: var(--white);
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 20px;
        }

        .stat-number {
            font-size: 24px;
            font-weight: 900;
            color: var(--black);
        }

        .stat-label {
            font-size: 13px;
            color: var(--gray-600);
        }

        /* FILTER TABS */
        .filter-tabs {
            padding: 24px 40px;
            background: var(--white);
            border-bottom: 2px solid var(--gray-200);
            position: sticky;
            top: 76px;
            z-index: 100;
        }

        .tabs-container {
            max-width: 1400px;
            margin: 0 auto;
            display: flex;
            gap: 12px;
            overflow-x: auto;
        }

        .tab-btn {
            padding: 10px 24px;
            background: transparent;
            border: 2px solid var(--gray-200);
            color: var(--black);
            font-size: 14px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            white-space: nowrap;
        }

        .tab-btn:hover,
        .tab-btn.active {
            background: var(--brand-blue);
            border-color: var(--brand-blue);
            color: var(--white);
        }

        /* LESSONS CONTAINER */
        .lessons-section {
            padding: 60px 40px;
        }

        .lessons-container {
            max-width: 1400px;
            margin: 0 auto;
        }

        .module-group {
            margin-bottom: 48px;
        }

        .module-group-title {
            font-size: 24px;
            font-weight: 800;
            margin-bottom: 24px;
            display: flex;
            align-items: center;
            gap: 16px;
        }

        .module-badge {
            background: var(--brand-blue);
            color: var(--white);
            padding: 6px 16px;
            font-size: 13px;
            font-weight: 700;
        }

        .lessons-grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 20px;
        }

        .lesson-card {
            background: var(--white);
            border: 2px solid var(--gray-200);
            padding: 24px;
            cursor: pointer;
            transition: all 0.3s;
            display: flex;
            align-items: start;
            gap: 16px;
        }

        .lesson-card:hover {
            border-color: var(--brand-blue);
            transform: translateY(-4px);
            box-shadow: 0 12px 30px rgba(0, 0, 0, 0.08);
        }

        .lesson-card.completed {
            background: rgba(16, 185, 129, 0.05);
            border-color: var(--success);
        }

        .lesson-status-icon {
            width: 40px;
            height: 40px;
            border: 2px solid var(--gray-300);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            flex-shrink: 0;
            font-size: 14px;
        }

        .lesson-card.completed .lesson-status-icon {
            background: var(--success);
            border-color: var(--success);
            color: var(--white);
        }

        .lesson-card.locked .lesson-status-icon {
            background: var(--gray-100);
            color: var(--gray-300);
        }

        .lesson-info {
            flex: 1;
        }

        .lesson-number-tag {
            font-size: 12px;
            font-weight: 700;
            color: var(--brand-blue);
            text-transform: uppercase;
            margin-bottom: 6px;
        }

        .lesson-title {
            font-size: 16px;
            font-weight: 700;
            margin-bottom: 8px;
            line-height: 1.4;
        }

        .lesson-meta {
            display: flex;
            gap: 16px;
            font-size: 13px;
            color: var(--gray-600);
        }

        .lesson-meta span {
            display: flex;
            align-items: center;
            gap: 6px;
        }

        /* FOOTER */
        .footer {
            background: var(--gray-900);
            color: var(--white);
            padding: 80px 40px 40px;
        }

        .footer-content {
            max-width: 1400px;
            margin: 0 auto;
            display: grid;
            grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
            gap: 60px;
            margin-bottom: 60px;
        }

        .footer-logo {
            font-size: 28px;
            font-weight: 800;
            margin-bottom: 20px;
        }

        .footer-tagline {
            font-size: 15px;
            color: var(--gray-300);
            line-height: 1.7;
        }

        .footer-column h4 {
            font-size: 14px;
            font-weight: 700;
            text-transform: uppercase;
            margin-bottom: 24px;
        }

        .footer-links {
            list-style: none;
        }

        .footer-links li {
            margin-bottom: 16px;
        }

        .footer-links a {
            color: var(--gray-300);
            text-decoration: none;
            font-size: 15px;
            transition: color 0.2s;
        }

        .footer-links a:hover {
            color: var(--white);
        }

        .footer-bottom {
            max-width: 1400px;
            margin: 0 auto;
            padding-top: 40px;
            border-top: 1px solid var(--gray-600);
            text-align: center;
            color: var(--gray-300);
            font-size: 14px;
        }

        @media (max-width: 1200px) {
            .lessons-grid {
                grid-template-columns: repeat(2, 1fr);
            }

            .footer-content {
                grid-template-columns: repeat(2, 1fr);
            }
        }

        @media (max-width: 768px) {
            .nav-center {
                display: none;
            }

            .lessons-grid {
                grid-template-columns: 1fr;
            }

            .stats-bar {
                gap: 20px;
            }

            .footer-content {
                grid-template-columns: 1fr;
            }
        }

        html {
            scroll-behavior: smooth;
        }

        /* ==================== ADDITIONAL RESPONSIVE & MOBILE OVERFLOW SAFEGUARDS ==================== */
        @media (max-width: 768px) {
            .nav-container {
                padding: 16px 20px !important;
            }

            .breadcrumb-section {
                padding: 110px 20px 24px !important;
            }

            .archive-hero,
            .lessons-section {
                padding: 40px 20px !important;
            }

            .filter-tabs {
                padding: 16px 20px !important;
                top: 70px !important;
            }
        }

        @media (max-width: 480px) {
            .breadcrumb-section {
                padding: 100px 16px 20px !important;
            }

            .archive-hero,
            .lessons-section,
            .filter-tabs {
                padding-left: 16px !important;
                padding-right: 16px !important;
            }

            .lesson-card {
                padding: 18px 16px !important;
            }

            .search-input {
                padding: 14px 16px 14px 48px !important;
                font-size: 14px !important;
            }
        }