.catalog-wrap {
        max-width: 1280px;
        margin: 0 auto;
        padding: 1rem 1.1rem 2rem;
    }

    .catalog-grid {
        display: grid;
        grid-template-columns: 300px minmax(0, 1fr);
        gap: 1rem;
        align-items: start;
    }

    .catalog-sidebar {
        position: sticky;
        top: calc(var(--nav-h) + 1rem);
        max-height: calc(100vh - var(--nav-h) - 2rem);
        overflow: hidden;
        background: var(--bd-surface);
        border: 1px solid var(--bd-border);
        border-radius: var(--r-2xl);
        box-shadow: var(--shadow-sm);
    }

    .sidebar-search {
        padding: .95rem;
        border-bottom: 1px solid var(--bd-divider);
        background: var(--bd-surface-2);
    }

    .sidebar-search label {
        display: flex;
        align-items: center;
        gap: .45rem;
        font-size: .75rem;
        font-weight: 800;
        text-transform: uppercase;
        letter-spacing: .07em;
        color: var(--bd-primary);
        margin-bottom: .45rem;
    }

    .sidebar-helper {
        margin: -.2rem 0 .55rem;
        color: var(--bd-text-muted);
        font-size: .78rem;
        line-height: 1.4;
    }

    .sidebar-search input {
        width: 100%;
        height: 42px;
        border: 1.5px solid var(--bd-border);
        border-radius: var(--r-lg);
        background: var(--bd-surface);
        color: var(--bd-text);
        padding: 0 .85rem;
        font-size: .9rem;
        outline: none;
        transition: border-color var(--t-fast), box-shadow var(--t-fast);
    }

    .sidebar-search input:focus {
        border-color: var(--bd-primary);
        box-shadow: 0 0 0 3px rgba(1,105,111,.10);
    }

    .catalog-tree {
        max-height: calc(100vh - var(--nav-h) - 8rem);
        overflow-y: auto;
        padding: .4rem 0;
    }

    .catalog-section {
        border-bottom: 1px solid var(--bd-divider);
    }

    .catalog-section:last-child {
        border-bottom: 0;
    }

    .catalog-sec-btn {
        width: 100%;
        border: 0;
        background: transparent;
        display: flex;
        align-items: center;
        gap: .6rem;
        text-align: left;
        padding: .8rem .95rem;
        cursor: pointer;
        transition: background var(--t-fast);
    }

    .catalog-sec-btn:hover,
    .catalog-section.open .catalog-sec-btn {
        background: var(--bd-primary-light);
    }

    .catalog-sec-num {
        width: 28px;
        height: 28px;
        border-radius: var(--r-sm);
        background: var(--bd-primary);
        color: #fff;
        display: inline-flex;
        align-items: center;
        justify-content: center;
        font-size: .72rem;
        font-weight: 800;
        flex-shrink: 0;
    }

    .catalog-sec-title {
        flex: 1;
        min-width: 0;
        font-size: .88rem;
        font-weight: 700;
        color: var(--bd-text);
        line-height: 1.35;
    }

    .catalog-sec-count {
        font-size: .72rem;
        color: var(--bd-text-faint);
        white-space: nowrap;
        flex-shrink: 0;
    }

    .catalog-arrow {
        font-size: .72rem;
        color: var(--bd-text-faint);
        transition: transform var(--t-base);
        flex-shrink: 0;
    }

    .catalog-section.open .catalog-arrow {
        transform: rotate(90deg);
    }

    .catalog-chapters {
        display: none;
        border-top: 1px solid var(--bd-divider);
        background: var(--bd-surface-2);
    }

    .catalog-chapters.open {
        display: block;
    }

    .catalog-chapter-link {
        display: flex;
        align-items: center;
        gap: .6rem;
        padding: .62rem .95rem .62rem 2.3rem;
        color: var(--bd-text-muted);
        font-size: .84rem;
        border-bottom: 1px solid var(--bd-divider);
        transition: background var(--t-fast), color var(--t-fast);
    }

    .catalog-chapter-link:last-child {
        border-bottom: 0;
    }

    .catalog-chapter-link:hover,
    .catalog-chapter-link.active {
        background: var(--bd-primary-light);
        color: var(--bd-primary);
    }

    .catalog-ch-num {
        font-size: .72rem;
        font-weight: 800;
        color: var(--bd-primary);
        background: var(--bd-surface);
        border: 1px solid var(--bd-primary-mid);
        border-radius: var(--r-sm);
        padding: .12rem .42rem;
        white-space: nowrap;
        flex-shrink: 0;
    }

    .catalog-ch-name {
        flex: 1;
        min-width: 0;
        line-height: 1.35;
    }

    .catalog-main {
        min-width: 0;
    }

    .catalog-head {
        background: var(--bd-surface);
        border: 1px solid var(--bd-border);
        border-radius: var(--r-2xl);
        box-shadow: var(--shadow-sm);
        padding: 1rem 1.15rem;
        margin-bottom: 1rem;
    }

    .catalog-h1 {
        font-size: var(--fs-h1, clamp(1.5rem, 2.6vw, 2.1rem));
        font-weight: 800;
        line-height: var(--lh-tight, 1.2);
        letter-spacing: -.02em;
        margin: .2rem 0 .55rem;
    }

    .catalog-lead {
        color: var(--bd-text-muted);
        font-size: .96rem;
        line-height: 1.7;
        max-width: 74ch;
        margin: 0;
    }

    .catalog-meta-row {
        display: flex;
        align-items: center;
        gap: .55rem;
        flex-wrap: wrap;
        margin-top: .95rem;
    }

    .meta-chip {
        display: inline-flex;
        align-items: center;
        gap: .35rem;
        padding: .32rem .68rem;
        border-radius: 999px;
        border: 1px solid var(--bd-border);
        background: var(--bd-surface-2);
        color: var(--bd-text-muted);
        font-size: .79rem;
        font-weight: 600;
    }

    .chapter-filter-card,
    .heading-block,
    .overview-card,
    .catalog-empty,
    .heading-empty {
        background: var(--bd-surface);
        border: 1px solid var(--bd-border);
        border-radius: var(--r-2xl);
        box-shadow: var(--shadow-sm);
    }

    .chapter-filter-card {
        padding: .95rem 1rem;
        margin-bottom: 1rem;
    }

    .chapter-filter-row {
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: .8rem;
        flex-wrap: wrap;
    }

    .chapter-filter-left,
    .chapter-filter-right {
        display: flex;
        align-items: center;
        gap: .75rem;
        flex-wrap: wrap;
    }

    .chapter-search-wrap {
        position: relative;
    }

    .chapter-search-wrap i {
        position: absolute;
        left: .75rem;
        top: 50%;
        transform: translateY(-50%);
        color: var(--bd-text-faint);
        font-size: .86rem;
    }

    .chapter-search {
        width: 250px;
        max-width: 100%;
        height: 40px;
        border: 1.5px solid var(--bd-border);
        border-radius: var(--r-lg);
        background: var(--bd-surface-2);
        color: var(--bd-text);
        padding: 0 .85rem 0 2.2rem;
        outline: none;
        font-size: .88rem;
        transition: border-color var(--t-fast), box-shadow var(--t-fast);
    }

    .chapter-search:focus {
        border-color: var(--bd-primary);
        box-shadow: 0 0 0 3px rgba(1,105,111,.10);
    }

    .chapter-filter-count,
    .sort-label {
        font-size: .8rem;
        color: var(--bd-text-muted);
        font-weight: 600;
    }

    .sort-select {
        height: 40px;
        border: 1.5px solid var(--bd-border);
        border-radius: var(--r-lg);
        background: var(--bd-surface-2);
        color: var(--bd-text);
        padding: 0 .8rem;
        outline: none;
        font-size: .88rem;
    }

    .overview-card {
        padding: 1.1rem 1.15rem;
    }

    .overview-grid {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
        gap: .7rem;
        margin-top: .85rem;
    }

    .overview-box {
        display: flex;
        flex-direction: column;
        gap: .18rem;
        padding: .85rem .95rem;
        border: 1px solid var(--bd-border);
        border-radius: var(--r-xl);
        background: var(--bd-surface-2);
        transition: border-color var(--t-fast), background var(--t-fast), box-shadow var(--t-fast);
    }

    .overview-box:hover {
        background: var(--bd-primary-light);
        border-color: var(--bd-primary-mid);
        box-shadow: var(--shadow-sm);
        color: var(--bd-primary);
    }

    .overview-ch {
        font-size: .78rem;
        font-weight: 800;
        color: var(--bd-primary);
    }

    .overview-name {
        font-size: .84rem;
        color: var(--bd-text-muted);
        line-height: 1.4;
    }

    .heading-block {
        overflow: hidden;
        margin-bottom: 1rem;
    }

    .heading-header {
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: .75rem;
        flex-wrap: wrap;
        padding: .9rem 1rem;
        background: var(--bd-surface-2);
        border-bottom: 1px solid var(--bd-border);
    }

    .heading-title-wrap {
        display: flex;
        align-items: center;
        gap: .65rem;
        min-width: 0;
    }

    .heading-code {
        font-family: "Courier New", monospace;
        font-size: .84rem;
        font-weight: 700;
        color: var(--bd-primary);
        background: var(--bd-primary-light);
        padding: .18rem .5rem;
        border-radius: var(--r-sm);
        white-space: nowrap;
        flex-shrink: 0;
    }

    .heading-title {
        font-size: .96rem;
        font-weight: 700;
        color: var(--bd-text);
        line-height: 1.35;
        margin: 0;
    }

    .heading-count {
        font-size: .8rem;
        color: var(--bd-text-muted);
        font-weight: 600;
        white-space: nowrap;
    }

    .table-wrap {
        overflow-x: auto;
    }

    .hs-table {
        width: 100%;
        border-collapse: collapse;
        font-size: .84rem;
    }

    .hs-table thead th {
        background: var(--bd-surface);
        padding: .7rem .8rem;
        border-bottom: 1px solid var(--bd-border);
        font-size: .72rem;
        font-weight: 800;
        color: var(--bd-text-muted);
        text-transform: uppercase;
        letter-spacing: .05em;
        white-space: nowrap;
        text-align: left;
    }

    .hs-table td {
        padding: .78rem .8rem;
        border-bottom: 1px solid var(--bd-divider);
        vertical-align: top;
        color: var(--bd-text);
    }

    .hs-table tbody tr:last-child td {
        border-bottom: 0;
    }

    .hs-table tbody tr:hover td {
        background: var(--bd-surface-2);
    }

    .hs-table tr.tr-restricted td {
        background: rgba(180,83,9,.06);
    }

    .td-center {
        text-align: center;
    }

    .td-right {
        text-align: right;
    }

    .hs-code-chip {
        display: inline-flex;
        align-items: center;
        gap: .35rem;
        font-family: "Courier New", monospace;
        font-size: .82rem;
        font-weight: 700;
        color: var(--bd-primary);
        background: var(--bd-primary-light);
        border-radius: var(--r-sm);
        padding: .18rem .48rem;
        white-space: nowrap;
    }

    .hs-desc {
        font-size: .86rem;
        line-height: 1.5;
        color: var(--bd-text);
        min-width: 280px;
    }

    .hs-meta {
        display: flex;
        align-items: center;
        gap: .35rem;
        flex-wrap: wrap;
        margin-top: .3rem;
    }

    .hs-unit,
    .hs-restricted {
        display: inline-flex;
        align-items: center;
        gap: .25rem;
        font-size: .7rem;
        font-weight: 700;
        padding: .12rem .42rem;
        border-radius: 999px;
    }

    .hs-unit {
        background: var(--bd-surface-2);
        border: 1px solid var(--bd-border);
        color: var(--bd-text-muted);
    }

    .hs-restricted {
        background: #fff7ed;
        border: 1px solid #fed7aa;
        color: #c2410c;
    }

    .rate-pill {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        min-width: 56px;
        padding: .18rem .45rem;
        border-radius: var(--r-sm);
        background: var(--bd-surface-2);
        border: 1px solid var(--bd-border);
        color: var(--bd-text);
        font-size: .79rem;
        font-weight: 700;
        font-variant-numeric: tabular-nums;
    }

    .btn-calc-row {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: .4rem;
        min-height: 36px;
        padding: .45rem .8rem;
        border-radius: var(--r-md);
        border: 1px solid var(--bd-primary-mid);
        background: transparent;
        color: var(--bd-primary);
        font-size: .8rem;
        font-weight: 700;
        transition: all var(--t-fast);
        white-space: nowrap;
    }

    .btn-calc-row:hover {
        background: var(--bd-primary-light);
        border-color: var(--bd-primary);
        color: var(--bd-primary);
    }

    .catalog-empty,
    .heading-empty {
        padding: 2rem 1.2rem;
        text-align: center;
        color: var(--bd-text-muted);
    }

    .catalog-empty i,
    .heading-empty i {
        display: inline-flex;
        width: 54px;
        height: 54px;
        align-items: center;
        justify-content: center;
        border-radius: 50%;
        background: var(--bd-surface-2);
        color: var(--bd-text-faint);
        font-size: 1.25rem;
        margin-bottom: .85rem;
    }

    .catalog-empty h2,
    .heading-empty h3 {
        font-size: 1.05rem;
        font-weight: 700;
        margin-bottom: .3rem;
    }

    .catalog-empty p,
    .heading-empty p {
        margin: 0;
        font-size: .9rem;
        line-height: 1.6;
    }

    @media (max-width: 1080px) {
        .catalog-grid {
            grid-template-columns: 1fr;
        }

        .catalog-sidebar {
            position: static;
            max-height: none;
        }

        .catalog-tree {
            max-height: 420px;
        }
    }

    @media (max-width: 640px) {
        .catalog-wrap {
            padding: 1rem .85rem 2rem;
        }

        .catalog-head,
        .chapter-filter-card,
        .heading-block,
        .overview-card,
        .catalog-empty,
        .heading-empty,
        .catalog-sidebar {
            border-radius: var(--r-xl);
        }

        .catalog-head,
        .chapter-filter-card,
        .overview-card {
            padding: 1rem;
        }

        .heading-header {
            padding: .85rem .9rem;
        }

        .chapter-filter-row,
        .chapter-filter-left,
        .chapter-filter-right {
            flex-direction: column;
            align-items: stretch;
            width: 100%;
        }

        .chapter-search {
            width: 100%;
        }

        .hs-table thead th,
        .hs-table td {
            padding: .7rem .65rem;
        }

        .hs-desc {
            min-width: 220px;
        }
    }

    /* ────────────────────────────────────────────────────────────
       PR 5: catalog polish — slim filter chips
       ──────────────────────────────────────────────────────────── */
    .catalog-filter-chips {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: .35rem;
        margin-top: .65rem;
        padding-top: .65rem;
        border-top: 1px solid var(--bd-divider, var(--bd-border));
    }
    .catalog-filter-chips .cat-chip {
        appearance: none;
        background: var(--bd-surface);
        color: var(--bd-text-muted);
        border: 1px solid var(--bd-border);
        border-radius: 999px;
        padding: .25rem .7rem;
        font-size: var(--fs-small, .82rem);
        font-weight: 600;
        line-height: 1.2;
        cursor: pointer;
        transition: background var(--t-fast, .15s) ease, color var(--t-fast, .15s) ease, border-color var(--t-fast, .15s) ease;
    }
    .catalog-filter-chips .cat-chip:hover {
        color: var(--bd-text);
        border-color: var(--bd-text-muted);
    }
    .catalog-filter-chips .cat-chip.active {
        background: var(--bd-primary);
        color: #fff;
        border-color: var(--bd-primary);
    }
    .catalog-filter-chips .cat-chip:focus-visible {
        outline: none;
        box-shadow: var(--ring-focus, 0 0 0 3px rgba(1, 105, 111, .18));
    }
    .catalog-filter-chips .cat-chip-hint {
        margin-left: auto;
        font-size: var(--fs-label, .72rem);
        color: var(--bd-text-faint);
        letter-spacing: .04em;
    }
    .catalog-filter-chips .cat-chip-hint kbd {
        display: inline-block;
        padding: 0 .35rem;
        font-size: .68rem;
        font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
        background: var(--bd-surface-2);
        border: 1px solid var(--bd-border);
        border-radius: var(--r-sm, .35rem);
        color: var(--bd-text);
    }
    @media (max-width: 600px) {
        .catalog-filter-chips .cat-chip-hint { display: none; }
    }

    
    [data-hs-row].kb-focus > td:first-child {
        box-shadow: inset 2px 0 0 var(--bd-primary);
    }

    /* Dark-mode adaptation for the restricted-item badge (was light-only). */
    [data-theme="dark"] .hs-restricted {
        background: rgba(234, 88, 12, .14);
        border-color: rgba(234, 88, 12, .32);
        color: #fdba74;
    }

    /* Mobile touch targets — raise the per-row calculate button to 44px. */
    @media (max-width: 768px) {
        .btn-calc-row {
            min-height: 44px;
        }
    }

    /* Premium glassmorphism — catalog surfaces (palette unchanged). */
    @supports ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
        .catalog-sidebar,
        .catalog-head,
        .chapter-filter-card,
        .heading-block,
        .overview-card,
        .catalog-empty,
        .heading-empty {
            background: var(--glass-bg);
            border: 1px solid var(--glass-border);
            -webkit-backdrop-filter: blur(var(--glass-blur)) saturate(var(--glass-saturate));
            backdrop-filter: blur(var(--glass-blur)) saturate(var(--glass-saturate));
            box-shadow: var(--glass-shadow);
        }
        /* Sub-headers inside heading blocks stay readable. */
        .heading-header { background: color-mix(in srgb, var(--bd-surface-2) 70%, transparent); }
    }