/**
 * Index page shell — matches reference mock (body.dsa-index-ref).
 * Mind-map node UI stays in styles.css / script (no .graph/.node rules here).
 */
body.dsa-index-ref {
    --bg-1: #dfe9f3;
    --bg-2: #f5e6d3;
    --bg-3: #cfe7d8;
    --bg-4: #bfd9e6;
    --ink: #0f1720;
    --ink-2: #3a4452;
    --muted: #6b7480;
    --line: rgba(15, 23, 32, 0.08);
    --glass: rgba(255, 255, 255, 0.55);
    --glass-2: rgba(255, 255, 255, 0.35);
    --accent: #1f2a37;
    --accent-2: #0f1720;
    --pill: rgba(255, 255, 255, 0.7);
    --shadow: 0 20px 60px rgba(20, 30, 50, 0.12), 0 2px 8px rgba(20, 30, 50, 0.06);
    margin: 0;
    font-family:
        -apple-system,
        BlinkMacSystemFont,
        "SF Pro Display",
        "Inter",
        system-ui,
        sans-serif;
    color: var(--ink);
    background:
        radial-gradient(1100px 700px at 85% 10%, #f3e3cf 0%, transparent 60%),
        radial-gradient(900px 700px at 10% 90%, #cfe1f0 0%, transparent 55%),
        radial-gradient(900px 600px at 90% 90%, #bfe1d4 0%, transparent 60%),
        linear-gradient(135deg, #e9eef3, #dde6ee);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

body.dsa-index-ref .nav {
    position: sticky;
    top: 0;
    z-index: 50;
    backdrop-filter: blur(20px) saturate(160%);
    -webkit-backdrop-filter: blur(20px) saturate(160%);
    background: rgba(255, 255, 255, 0.55);
    border-bottom: 1px solid var(--line);
}

body.dsa-index-ref .nav-inner {
    max-width: 1400px;
    margin: 0 auto;
    height: 58px;
    padding: 0 22px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-sizing: border-box;
}

body.dsa-index-ref .nav .brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    letter-spacing: -0.01em;
    font-size: 15px;
    color: var(--ink);
    text-decoration: none;
}

body.dsa-index-ref .nav .brand-mark {
    width: 28px;
    height: 28px;
    border-radius: 8px;
    background: linear-gradient(135deg, #2a3442, #0f1720);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 13px;
    font-weight: 800;
    box-shadow:
        0 4px 12px rgba(15, 23, 32, 0.25),
        inset 0 1px 0 rgba(255, 255, 255, 0.18);
}

body.dsa-index-ref .nav .nav-links {
    display: flex;
    align-items: center;
    gap: 4px;
}

body.dsa-index-ref .nav .nav-links a {
    padding: 8px 14px;
    font-size: 13.5px;
    font-weight: 600;
    color: var(--ink-2);
    text-decoration: none;
    border-radius: 10px;
    transition: 0.2s;
}

body.dsa-index-ref .nav .nav-links a:hover {
    background: rgba(255, 255, 255, 0.6);
    color: var(--ink);
}

body.dsa-index-ref .nav .nav-links a.active {
    background: #fff;
    color: var(--ink);
    box-shadow:
        0 1px 2px rgba(0, 0, 0, 0.06),
        0 4px 12px rgba(0, 0, 0, 0.05);
}

body.dsa-index-ref .nav .nav-auth {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}

body.dsa-index-ref .nav .nav-auth .nav-admin-entry {
    padding: 8px 14px;
    font-size: 13.5px;
    font-weight: 600;
    color: var(--ink-2);
    text-decoration: none;
    border-radius: 10px;
    transition: 0.2s;
    white-space: nowrap;
}

body.dsa-index-ref .nav .nav-auth .nav-admin-entry:hover {
    background: rgba(255, 255, 255, 0.6);
    color: var(--ink);
}

body.dsa-index-ref .nav .signout {
    height: 36px;
    padding: 0 14px;
    border-radius: 10px;
    border: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.6);
    font-size: 13px;
    font-weight: 600;
    color: var(--ink-2);
    cursor: pointer;
    font-family: inherit;
    transition: 0.2s;
}

body.dsa-index-ref .nav .signout:hover {
    background: #fff;
    transform: translateY(-1px);
}

/* After wireMobileNav(): links + signout wrapped in .right for the slide-down panel. */
body.dsa-index-ref .nav .right {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}

/* Desktop: brand left | DSA + CMS centered | Login + Sign out in .nav-auth flush right */
@media (min-width: 721px) {
    body.dsa-index-ref .nav-inner {
        display: grid;
        grid-template-columns: 1fr auto 1fr;
        align-items: center;
        column-gap: 16px;
        justify-content: initial;
    }

    body.dsa-index-ref .nav .brand {
        grid-column: 1;
        justify-self: start;
    }

    body.dsa-index-ref .nav .right {
        display: contents;
    }

    body.dsa-index-ref .nav .nav-links {
        grid-column: 2;
        justify-self: center;
    }

    body.dsa-index-ref .nav .nav-auth {
        grid-column: 3;
        justify-self: end;
        justify-content: flex-end;
    }
}

@media (max-width: 720px) {
    body.dsa-index-ref .nav {
        position: relative;
        flex-wrap: wrap;
        height: auto;
        min-height: 58px;
    }

    body.dsa-index-ref .nav .nav-inner {
        display: flex;
        position: relative;
        height: auto;
        min-height: 58px;
        flex-wrap: wrap;
        row-gap: 10px;
        width: 100%;
        justify-content: space-between;
    }

    body.dsa-index-ref .nav .brand {
        flex: 1 1 auto;
        min-width: 0;
    }

    body.dsa-index-ref .nav .right {
        position: absolute;
        left: 12px;
        right: 12px;
        top: calc(100% + 8px);
        display: flex;
        flex-direction: column;
        align-items: stretch;
        gap: 6px;
        padding: 12px;
        margin: 0;
        max-width: none;
        background: rgba(255, 255, 255, 0.96);
        backdrop-filter: blur(20px) saturate(160%);
        -webkit-backdrop-filter: blur(20px) saturate(160%);
        border: 1px solid var(--line);
        border-radius: 16px;
        box-shadow: var(--shadow);
        z-index: 1001;
        max-height: min(72vh, 440px);
        overflow-x: hidden;
        overflow-y: auto;
        -webkit-overflow-scrolling: touch;
        opacity: 0;
        visibility: hidden;
        transform: translateY(-10px) scale(0.98);
        pointer-events: none;
        transition:
            opacity 0.22s ease,
            transform 0.22s ease,
            visibility 0.22s;
    }

    body.dsa-index-ref .nav.nav--menu-open .right {
        opacity: 1;
        visibility: visible;
        transform: translateY(0) scale(1);
        pointer-events: auto;
    }

    body.dsa-index-ref .nav.nav--menu-open .nav-mobile-toggle {
        background: rgba(255, 255, 255, 0.85);
        border-color: rgba(15, 23, 32, 0.18);
        color: var(--ink);
    }

    body.dsa-index-ref .nav .right .nav-links {
        display: flex;
        flex-direction: column;
        align-items: stretch;
        gap: 6px;
        width: 100%;
    }

    body.dsa-index-ref .nav .right .nav-auth {
        display: flex;
        flex-direction: column;
        align-items: stretch;
        gap: 6px;
        width: 100%;
    }

    body.dsa-index-ref .nav .right .nav-links a,
    body.dsa-index-ref .nav .right .nav-auth .nav-admin-entry,
    body.dsa-index-ref .nav .right .nav-auth .nav-signout-btn {
        margin-left: 0;
        width: 100%;
        justify-content: center;
        text-align: center;
        padding: 14px 16px;
        border-radius: 12px;
        border: 1px solid var(--line);
        background: rgba(255, 255, 255, 0.65);
        box-sizing: border-box;
        color: var(--ink-2);
    }

    body.dsa-index-ref .nav .right .nav-links a:hover,
    body.dsa-index-ref .nav .right .nav-auth .nav-admin-entry:hover,
    body.dsa-index-ref .nav .right .nav-auth .nav-signout-btn:hover {
        background: #fff;
        color: var(--ink);
        border-color: rgba(15, 23, 32, 0.12);
    }
}

body.dsa-index-ref .page {
    max-width: 1400px;
    margin: 0 auto;
    padding: 24px 22px 40px;
    display: flex;
    flex-direction: column;
    gap: 18px;
    box-sizing: border-box;
}

body.dsa-index-ref .head {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 24px;
    padding: 4px 4px 0;
}

body.dsa-index-ref .head-text .eyebrow {
    font-size: 11px;
    letter-spacing: 0.18em;
    font-weight: 600;
    color: var(--muted);
    text-transform: uppercase;
    margin-bottom: 8px;
}

body.dsa-index-ref .head-text h1 {
    font-size: 34px;
    font-weight: 700;
    margin: 0 0 8px;
    letter-spacing: -0.02em;
    line-height: 1;
}

body.dsa-index-ref .head-text p {
    color: var(--ink-2);
    font-size: 13.5px;
    line-height: 1.5;
    margin: 0;
    max-width: 680px;
}

body.dsa-index-ref .head-text p b {
    color: var(--ink);
}

body.dsa-index-ref #dsa-shell-view-toolbar {
    flex-shrink: 0;
}

body.dsa-index-ref .seg,
body.dsa-index-ref .dsa-view-tabs.seg {
    display: inline-flex;
    background: var(--glass-2);
    backdrop-filter: blur(20px) saturate(140%);
    -webkit-backdrop-filter: blur(20px) saturate(140%);
    border: 1px solid var(--line);
    border-radius: 14px;
    padding: 4px;
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

/* Sliding white pill (thumb) — DSA view tabs only */
body.dsa-index-ref .dsa-view-tabs.dsa-seg-track {
    position: relative;
}

body.dsa-index-ref .dsa-view-tabs.dsa-seg-track > .dsa-seg-thumb {
    position: absolute;
    left: 0;
    top: 0;
    z-index: 0;
    pointer-events: none;
    border-radius: 10px;
    background: #fff;
    box-shadow:
        0 1px 2px rgba(0, 0, 0, 0.06),
        0 4px 14px rgba(0, 0, 0, 0.05);
    opacity: 0;
    transition:
        transform 0.32s cubic-bezier(0.25, 0.1, 0.25, 1),
        width 0.32s cubic-bezier(0.25, 0.1, 0.25, 1),
        height 0.32s cubic-bezier(0.25, 0.1, 0.25, 1),
        opacity 0.2s ease;
    will-change: transform, width, height;
}

@media (prefers-reduced-motion: reduce) {
    body.dsa-index-ref .dsa-view-tabs.dsa-seg-track > .dsa-seg-thumb {
        transition: opacity 0.15s ease;
    }
}

body.dsa-index-ref .seg .dsa-view-btn,
body.dsa-index-ref .dsa-view-tabs.seg .dsa-view-btn {
    appearance: none;
    border: 0;
    background: transparent;
    padding: 9px 16px;
    font-size: 13px;
    font-weight: 600;
    color: var(--ink-2);
    border-radius: 10px;
    cursor: pointer;
    transition: color 0.25s ease;
    font-family: inherit;
    white-space: nowrap;
    position: relative;
    z-index: 1;
}

body.dsa-index-ref .seg .dsa-view-btn.dsa-view-btn--active,
body.dsa-index-ref .dsa-view-tabs.seg .dsa-view-btn.dsa-view-btn--active {
    background: transparent;
    color: var(--ink);
    box-shadow: none;
}

body.dsa-index-ref .dsa-view-toolbar {
    margin: 0;
    width: auto;
    display: flex;
    flex-direction: row;
    align-items: flex-end;
    justify-content: flex-end;
}

body.dsa-index-ref .toolbar {
    background: var(--glass);
    backdrop-filter: blur(28px) saturate(160%);
    -webkit-backdrop-filter: blur(28px) saturate(160%);
    border: 1px solid rgba(255, 255, 255, 0.7);
    border-radius: 18px;
    padding: 14px 16px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 14px;
    flex-wrap: wrap;
    position: relative;
    overflow: hidden;
}

body.dsa-index-ref .toolbar::before {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.45), rgba(255, 255, 255, 0) 40%);
    pointer-events: none;
}

body.dsa-index-ref #dsa-map-toolbar-host {
    display: flex;
    align-items: center;
    flex: 1;
    min-width: 0;
    position: relative;
    z-index: 1;
}

body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar {
    flex: 1;
    min-width: 0;
    margin: 0;
    padding: 0;
    border: 0;
    box-shadow: none;
    background: transparent;
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
    border-radius: 0;
}

body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar::before {
    display: none;
}

body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar {
    justify-content: flex-start;
    flex-wrap: nowrap;
    gap: 10px 14px;
}

body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar-cluster {
    gap: 8px;
}

/* Hint + leading dot, immediately left of zoom (margin-left: auto pulls hint+zoom right). */
body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar-hint {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-left: auto;
    flex: 0 1 auto;
    min-width: 0;
    max-width: min(480px, 46vw);
    font-size: 12px;
    line-height: 1.35;
    font-weight: 500;
    color: var(--muted);
}

body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar-hint .dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: linear-gradient(135deg, #2a3442, #0f1720);
    flex-shrink: 0;
}

body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar-hint-text {
    min-width: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    text-align: left;
}

body.dsa-index-ref #dsa-map-toolbar-host .dsa-graph-map-toolbar-cluster--zoom {
    margin-left: 0;
    flex-shrink: 0;
}

/* Expand / collapse — match reference .btn */
body.dsa-index-ref #dsa-map-toolbar-host .btn {
    height: 36px;
    padding: 0 12px;
    border-radius: 10px;
    border: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.6);
    font-size: 12.5px;
    font-weight: 600;
    color: var(--ink-2);
    cursor: pointer;
    font-family: inherit;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    transition: 0.2s;
    box-shadow: none;
}

body.dsa-index-ref #dsa-map-toolbar-host .btn:hover {
    background: #fff;
    transform: translateY(-1px);
    color: var(--ink);
}

body.dsa-index-ref #dsa-map-toolbar-host .btn svg {
    width: 14px;
    height: 14px;
    flex-shrink: 0;
}

/* Zoom — match reference .zoom (mounted toolbar only) */
body.dsa-index-ref #dsa-map-toolbar-host .zoom {
    display: inline-flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.6);
    border: 1px solid var(--line);
    border-radius: 10px;
    overflow: hidden;
}

body.dsa-index-ref #dsa-map-toolbar-host .zoom button {
    width: 32px;
    height: 34px;
    border: 0;
    background: transparent;
    cursor: pointer;
    color: var(--ink-2);
    font-size: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: 0.15s;
    font-family: inherit;
    padding: 0;
}

body.dsa-index-ref #dsa-map-toolbar-host .zoom button:hover {
    background: rgba(255, 255, 255, 0.9);
    color: var(--ink);
}

body.dsa-index-ref #dsa-map-toolbar-host .zoom .val {
    padding: 0 10px;
    font-size: 12px;
    font-weight: 600;
    color: var(--ink-2);
    border-left: 1px solid var(--line);
    border-right: 1px solid var(--line);
    height: 34px;
    display: flex;
    align-items: center;
    font-variant-numeric: tabular-nums;
}

body.dsa-index-ref .graph-card {
    background: var(--glass);
    backdrop-filter: blur(28px) saturate(160%);
    -webkit-backdrop-filter: blur(28px) saturate(160%);
    border: 1px solid rgba(255, 255, 255, 0.7);
    border-radius: 22px;
    padding: 8px;
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
}

body.dsa-index-ref .graph-card::before {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.5), rgba(255, 255, 255, 0) 30%);
    pointer-events: none;
    border-radius: 22px;
}

body.dsa-index-ref .graph-stage {
    position: relative;
    border-radius: 16px;
    background:
        radial-gradient(800px 500px at 80% 20%, rgba(243, 227, 207, 0.55), transparent 60%),
        radial-gradient(700px 500px at 15% 85%, rgba(207, 225, 240, 0.55), transparent 60%),
        linear-gradient(180deg, rgba(255, 255, 255, 0.6), rgba(255, 255, 255, 0.3));
    border: 1px solid rgba(255, 255, 255, 0.7);
    overflow: auto;
    min-height: 560px;
}

body.dsa-index-ref .foot {
    text-align: center;
    color: var(--muted);
    font-size: 11.5px;
    margin-top: 6px;
    line-height: 1.5;
}

body.dsa-index-ref .foot a {
    color: var(--ink-2);
    text-decoration: none;
    font-weight: 600;
}

body.dsa-index-ref .dsa-index-site-footer.footer {
    background: rgba(255, 255, 255, 0.38);
    backdrop-filter: blur(18px) saturate(130%);
    -webkit-backdrop-filter: blur(18px) saturate(130%);
    border-top: 1px solid rgba(255, 255, 255, 0.5);
    min-height: auto;
}

body.dsa-index-ref .dsa-index-site-footer .footer-bottom {
    border-top-color: rgba(15, 23, 32, 0.08);
}

body.dsa-index-ref .dsa-index-site-footer .footer-copyright p {
    color: var(--ink-2);
}

body.dsa-index-ref .dsa-graph-hint--shell-external {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* —— Practice problem card + solution UI (glass, index only) —— */
body.dsa-index-ref .dsa-h-problems-card {
    position: relative;
    background: var(--glass);
    backdrop-filter: blur(28px) saturate(160%);
    -webkit-backdrop-filter: blur(28px) saturate(160%);
    border: 1px solid rgba(255, 255, 255, 0.7);
    border-radius: 18px;
    box-shadow: var(--shadow);
    overflow: visible;
}

body.dsa-index-ref .dsa-h-problems-card::before {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.5), rgba(255, 255, 255, 0) 38%);
    pointer-events: none;
    z-index: 0;
}

body.dsa-index-ref .dsa-h-problems-card > * {
    position: relative;
    z-index: 1;
}

body.dsa-index-ref .dsa-h-problems-card-title {
    color: var(--ink-2);
}

body.dsa-index-ref .dsa-h-problems-empty {
    color: var(--muted);
}

body.dsa-index-ref .dsa-h-problems-filter-tabs {
    background: var(--glass-2);
    backdrop-filter: blur(20px) saturate(140%);
    -webkit-backdrop-filter: blur(20px) saturate(140%);
    border: 1px solid var(--line);
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

body.dsa-index-ref .dsa-h-problems-tools-tab {
    background: rgba(255, 255, 255, 0.5);
    backdrop-filter: blur(12px) saturate(130%);
    -webkit-backdrop-filter: blur(12px) saturate(130%);
    border: 1px solid var(--line);
    color: var(--ink-2);
}

body.dsa-index-ref .dsa-h-problems-tools-tab:hover {
    background: rgba(255, 255, 255, 0.75);
    color: var(--ink);
    border-color: rgba(15, 23, 32, 0.12);
}

body.dsa-index-ref .dsa-h-problems-tools-panel {
    background: var(--glass-2);
    backdrop-filter: blur(18px) saturate(140%);
    -webkit-backdrop-filter: blur(18px) saturate(140%);
    border: 1px solid rgba(255, 255, 255, 0.55);
}

body.dsa-index-ref .dsa-h-problems-tools-search-input {
    background: rgba(255, 255, 255, 0.72);
    border-color: var(--line);
    color: var(--ink);
}

body.dsa-index-ref .dsa-h-problems-diff-chip {
    background: rgba(255, 255, 255, 0.45);
    border-color: var(--line);
    color: var(--ink-2);
}

body.dsa-index-ref .dsa-h-problems-diff-chip:hover {
    background: rgba(255, 255, 255, 0.75);
    border-color: rgba(15, 23, 32, 0.1);
    color: var(--ink);
}

body.dsa-index-ref .dsa-h-problems-card-close,
body.dsa-index-ref .dsa-h-problems-card-delete-all {
    background: rgba(255, 255, 255, 0.55);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--line);
    color: var(--ink-2);
}

body.dsa-index-ref .dsa-h-problems-card-close:hover,
body.dsa-index-ref .dsa-h-problems-card-delete-all:hover {
    background: #fff;
    border-color: rgba(15, 23, 32, 0.12);
    color: var(--ink);
}

body.dsa-index-ref .dsa-h-sol-modern {
    background: var(--glass);
    backdrop-filter: blur(28px) saturate(160%);
    -webkit-backdrop-filter: blur(28px) saturate(160%);
    border: 1px solid rgba(255, 255, 255, 0.7);
    box-shadow: var(--shadow);
}

body.dsa-index-ref .dsa-h-sol-heading {
    color: var(--ink-2);
}

body.dsa-index-ref .dsa-h-sol-chip {
    background: rgba(255, 255, 255, 0.5);
    border-color: var(--line);
    color: var(--ink);
}

body.dsa-index-ref .dsa-h-sol-chip:hover {
    background: rgba(255, 255, 255, 0.82);
    border-color: rgba(15, 23, 32, 0.1);
}

body.dsa-index-ref .dsa-h-prob-hint,
body.dsa-index-ref .dsa-h-prob-companies {
    background: var(--glass-2);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--line);
    color: var(--ink-2);
}

body.dsa-index-ref .dsa-h-prob-pane-img {
    border-color: var(--line);
}

@media (max-width: 780px) {
    body.dsa-index-ref .head {
        flex-direction: column;
        align-items: flex-start;
        gap: 14px;
    }

    body.dsa-index-ref .head-text h1 {
        font-size: 28px;
    }

    body.dsa-index-ref .page {
        padding: 24px 20px 40px;
    }

    body.dsa-index-ref .nav-inner {
        padding: 0 18px;
    }

    body.dsa-index-ref .nav .nav-links a {
        padding: 7px 12px;
    }

    body.dsa-index-ref .dsa-view-toolbar {
        align-items: stretch;
        width: 100%;
        justify-content: stretch;
    }

    body.dsa-index-ref .dsa-view-toolbar .dsa-view-tabs.seg {
        width: 100%;
        justify-content: center;
    }
}