/* Highlights */
        .stats-strip {
            position: relative;
            z-index: 4;
            margin-top: -86px;
        }
        .stats-shell {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            overflow: hidden;
            border: 1px solid rgba(228,231,236,.85);
            border-radius: 22px;
            background: rgba(255,255,255,.9);
            box-shadow: var(--shadow-md);
            backdrop-filter: blur(16px);
        }
        .stat { padding: 24px; border-right: 1px solid var(--line); }
        .stat:last-child { border-right: 0; }
        .stat-value { display: block; color: var(--text-strong); font-size: 1.55rem; font-weight: 900; letter-spacing: -.035em; }
        .stat-label { display: block; margin-top: 2px; color: var(--text-muted); font-size: .88rem; }

        /* Subject Bento */
        .subject-grid {
            display: grid;
            grid-template-columns: repeat(12, 1fr);
            gap: 16px;
        }
        .subject-card {
            position: relative;
            grid-column: span 4;
            min-height: 230px;
            overflow: hidden;
            padding: 24px;
            border: 1px solid var(--line);
            border-radius: var(--radius-md);
            background: var(--surface);
            box-shadow: var(--shadow-sm);
            cursor: pointer;
            text-align: left;
            transition: transform var(--ease), box-shadow var(--ease), border-color var(--ease);
        }
        .subject-card:nth-child(1), .subject-card:nth-child(4) { grid-column: span 6; }
        .subject-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: rgba(76,141,255,.34); }
        .subject-icon {
            display: inline-grid;
            place-items: center;
            width: 46px;
            height: 46px;
            border-radius: 14px;
            color: #194fba;
            background: #eaf1ff;
            font-size: 1.1rem;
        }
        .subject-card h3 { margin: 34px 0 0; color: var(--text-strong); font-size: 1.36rem; line-height: 1.15; letter-spacing: -.025em; }
        .subject-card p { max-width: 410px; margin: 11px 0 0; color: var(--text-muted); font-size: .95rem; }
        .subject-arrow {
            position: absolute;
            top: 22px;
            right: 22px;
            display: grid;
            place-items: center;
            width: 38px;
            height: 38px;
            border: 1px solid var(--line);
            border-radius: 50%;
            color: #245fc8;
            background: white;
        }
        .subject-orbit {
            position: absolute;
            right: -55px;
            bottom: -75px;
            width: 210px;
            height: 210px;
            border: 1px solid rgba(76,141,255,.16);
            border-radius: 50%;
            box-shadow: 0 0 0 34px rgba(76,141,255,.035), 0 0 0 68px rgba(139,92,246,.025);
        }
        .subject-card[data-subject="calculus"] { background: linear-gradient(145deg, #fff, #f5f0ff); }
        .subject-card[data-subject="linear"] { background: linear-gradient(145deg, #fff, #fff8eb); }
        .subject-card[data-subject="engineering"] { background: linear-gradient(145deg, #fff, #ecfbff); }
        .subject-card[data-subject="formulas"] { background: linear-gradient(145deg, #fff, #fff0f7); }

        /* Featured */
        .featured-section { background: var(--surface); }
        .featured-grid {
            display: grid;
            grid-template-columns: repeat(3, minmax(0, 1fr));
            gap: 18px;
        }
        .lesson-card {
            position: relative;
            display: flex;
            flex-direction: column;
            min-height: 320px;
            overflow: hidden;
            border: 1px solid var(--line);
            border-radius: var(--radius-md);
            background: var(--surface);
            box-shadow: var(--shadow-sm);
            cursor: pointer;
            transition: transform var(--ease), box-shadow var(--ease), border-color var(--ease);
        }
        .lesson-card:hover { transform: translateY(-5px); border-color: rgba(76,141,255,.36); box-shadow: var(--shadow-md); }
        .lesson-art {
            position: relative;
            height: 138px;
            overflow: hidden;
            background:
                radial-gradient(circle at 75% 18%, rgba(255,255,255,.24), transparent 18%),
                linear-gradient(135deg, #101a36, #1d3b72);
        }
        .lesson-art::before, .lesson-art::after {
            content: "";
            position: absolute;
            border: 1px solid rgba(255,255,255,.24);
            border-radius: 50%;
        }
        .lesson-art::before { width: 160px; height: 160px; right: -30px; top: -60px; }
        .lesson-art::after { width: 100px; height: 100px; right: 35px; top: 20px; }
        .lesson-art i {
            position: absolute;
            left: 22px;
            bottom: 18px;
            color: white;
            font-size: 1.7rem;
        }
        .lesson-body { display: flex; flex: 1; flex-direction: column; padding: 22px; }
        .lesson-meta { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 12px; }
        .lesson-tag {
            padding: 5px 9px;
            border-radius: 999px;
            color: #245fc8;
            background: #edf3ff;
            font-size: .72rem;
            font-weight: 850;
        }
        .lesson-body h3 { margin: 0; color: var(--text-strong); font-size: 1.22rem; line-height: 1.3; letter-spacing: -.025em; }
        .lesson-body p { margin: 11px 0 18px; color: var(--text-muted); font-size: .92rem; }
        .lesson-cta {
            display: flex;
            align-items: center;
            justify-content: space-between;
            gap: 10px;
            margin-top: auto;
            padding-top: 14px;
            border-top: 1px solid var(--line);
            color: #245fc8;
            font-weight: 820;
            font-size: .9rem;
        }

        /* Catalog */
        .catalog-section { background: var(--surface-muted); }
        .catalog-toolbar {
            display: grid;
            grid-template-columns: minmax(250px, 1fr) auto;
            gap: 14px;
            align-items: center;
            margin-bottom: 18px;
        }
        .catalog-search {
            display: flex;
            align-items: center;
            gap: 10px;
            min-height: 50px;
            padding: 8px 14px;
            border: 1px solid var(--line);
            border-radius: 14px;
            background: white;
        }
        .catalog-search i { color: #98a2b3; }
        .catalog-search input { min-width: 0; flex: 1; border: 0; outline: 0; color: var(--text-strong); background: transparent; }
        .catalog-count { color: var(--text-muted); font-size: .9rem; white-space: nowrap; }
        .category-tabs {
            display: flex;
            gap: 8px;
            overflow-x: auto;
            margin: 0 0 24px;
            padding: 2px 2px 8px;
            scrollbar-width: none;
        }
        .category-tabs::-webkit-scrollbar { display: none; }
        .category-tab {
            min-height: 42px;
            padding: 7px 14px;
            border: 1px solid var(--line);
            border-radius: 999px;
            background: white;
            color: var(--text-muted);
            cursor: pointer;
            font-size: .88rem;
            font-weight: 750;
            white-space: nowrap;
        }
        .category-tab.active { border-color: var(--ink-900); background: var(--ink-900); color: white; }
        .catalog-grid {
            display: grid;
            grid-template-columns: repeat(3, minmax(0, 1fr));
            gap: 18px;
        }
        .empty-state {
            grid-column: 1 / -1;
            padding: 60px 24px;
            border: 1px dashed #cbd5e1;
            border-radius: var(--radius-md);
            background: white;
            text-align: center;
        }
        .empty-state i { color: #98a2b3; font-size: 2rem; }
        .empty-state h3 { margin: 14px 0 5px; color: var(--text-strong); }
        .empty-state p { margin: 0; color: var(--text-muted); }
        .load-more-row { display: flex; justify-content: center; margin-top: 30px; }
        .load-more {
            min-height: 48px;
            padding: 10px 18px;
            border: 1px solid var(--line);
            border-radius: 13px;
            background: white;
            color: var(--text-strong);
            cursor: pointer;
            font-weight: 820;
        }
        .load-more[hidden] { display: none; }