:root {
    --bg: #FFFFFF;
    --bg-deep: #F5F7FA;
    --bg-soft: #EEF1F6;
    --text: #1E2A3A;
    --title: #0A1628;
    --muted: #4A5568;
    --subtle: #718096;
    --brand: #0033A0;
    --brand-bright: #0052CC;
    --brand-deep: #002066;
    --border: rgba(0, 51, 160, 0.14);
    --shadow: 0 12px 36px rgba(0, 33, 102, 0.08);
    --radius: 14px;
    --topline-h: 22px;
    --masthead-h: 68px;
    --tabs-h: 44px;
    --fixed-h: 134px;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    background: var(--bg);
}

body {
    margin: 0;
    min-width: 0;
    overflow-x: hidden;
    background: var(--bg);
    color: var(--text);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
    font-size: 16px;
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
}

body.no-scroll {
    overflow: hidden;
}

a {
    color: var(--brand);
    text-decoration: none;
}

a:hover {
    color: var(--brand-bright);
}

button,
input {
    font: inherit;
}

button,
a {
    -webkit-tap-highlight-color: transparent;
}

button:focus-visible,
a:focus-visible,
input:focus-visible {
    outline: 3px solid rgba(0, 82, 204, 0.28);
    outline-offset: 3px;
}

img {
    max-width: 100%;
}

.site-width {
    width: min(1220px, calc(100% - 32px));
    margin: 0 auto;
}

.fixed-top {
    position: fixed;
    inset: 0 0 auto 0;
    z-index: 1200;
    background: #fff;
}

.blue-line {
    height: var(--topline-h);
    background: var(--brand-deep);
    color: #fff;
}

.blue-line-inner {
    position: relative;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 12px;
    letter-spacing: 0.04em;
}

.blue-line-brand {
    white-space: nowrap;
}

.top-search-button {
    position: absolute;
    right: 0;
    top: -11px;
    min-width: 58px;
    min-height: 44px;
    border: 0;
    border-radius: 0;
    background: transparent;
    color: #fff;
    cursor: pointer;
    font-weight: 700;
}

.top-search-button:hover {
    background: rgba(255, 255, 255, 0.1);
}

.masthead {
    height: var(--masthead-h);
    background: #fff;
    border-bottom: 1px solid var(--border);
}

.masthead-inner {
    height: 100%;
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    gap: 16px;
}

.masthead-logo {
    display: inline-flex;
    align-items: center;
    justify-self: start;
    min-width: 68px;
    min-height: 44px;
    color: var(--title);
}

.brand-logo {
    display: block;
    width: auto;
    max-width: 170px;
    height: 34px;
    object-fit: contain;
    object-position: left center;
}

.brand-wordmark {
    color: var(--brand-deep);
    font-size: 27px;
    font-weight: 900;
    letter-spacing: -0.04em;
}

.catalog-button,
.app-link,
.primary-button,
.secondary-button,
.panel-close {
    min-height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 9px 18px;
    border-radius: 10px;
    font-weight: 800;
    line-height: 1.2;
}

.catalog-button {
    border: 1px solid var(--brand);
    background: #fff;
    color: var(--brand);
    cursor: pointer;
}

.catalog-button:hover {
    background: var(--bg-soft);
}

.app-link {
    justify-self: end;
    background: linear-gradient(135deg, #0052CC 0%, #0033A0 50%, #002066 100%);
    color: #fff;
}

.app-link:hover,
.primary-button:hover {
    color: #fff;
    filter: brightness(1.04);
}

.tab-strip {
    height: var(--tabs-h);
    background: var(--bg-soft);
    border-bottom: 1px solid var(--border);
}

.tab-strip-inner {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 4px;
}

.tab-item {
    min-height: 36px;
    display: inline-flex;
    align-items: center;
    padding: 0 14px;
    border-radius: 8px;
    color: var(--muted);
    font-weight: 700;
    font-size: 14px;
}

.tab-item:hover {
    background: rgba(0, 51, 160, 0.07);
    color: var(--brand);
}

.tab-item.is-current {
    background: var(--brand);
    color: #fff;
}

main {
    padding-top: var(--fixed-h);
    min-height: 60vh;
}

.page-wrap {
    padding: 42px 0 72px;
}

.page-hero {
    padding: 34px 0 28px;
    background: linear-gradient(180deg, var(--bg-deep), #fff);
    border-bottom: 1px solid var(--border);
}

.page-hero-grid {
    display: grid;
    grid-template-columns: minmax(0, 1.25fr) minmax(260px, 0.75fr);
    gap: 28px;
    align-items: center;
}

.page-hero-copy {
    min-width: 0;
}

.eyebrow {
    display: inline-block;
    margin-bottom: 8px;
    color: var(--brand);
    font-size: 13px;
    font-weight: 900;
    letter-spacing: 0.08em;
}

h1,
h2,
h3,
p {
    overflow-wrap: anywhere;
}

h1 {
    margin: 0 0 14px;
    color: var(--title);
    font-size: clamp(28px, 3.1vw, 32px);
    line-height: 1.25;
    letter-spacing: -0.02em;
}

h2 {
    margin: 0 0 12px;
    color: var(--title);
    font-size: clamp(21px, 2vw, 25px);
    line-height: 1.35;
}

h3 {
    margin: 0 0 8px;
    color: var(--title);
    font-size: 18px;
    line-height: 1.4;
}

p {
    margin: 0 0 14px;
}

.lead {
    max-width: 820px;
    color: var(--muted);
    font-size: 17px;
    line-height: 1.85;
}

.hero-actions,
.section-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 20px;
}

.primary-button {
    background: linear-gradient(135deg, #0052CC 0%, #0033A0 50%, #002066 100%);
    color: #fff;
}

.secondary-button {
    border: 1px solid var(--brand);
    background: #fff;
    color: var(--brand);
}

.content-section {
    padding: 42px 0;
    border-bottom: 1px solid var(--border);
}

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

.section-head {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 20px;
}

.section-head p {
    max-width: 700px;
    margin: 0;
    color: var(--muted);
}

.media-frame {
    width: 100%;
    height: 220px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: linear-gradient(135deg, #F5F7FA, #EEF3FA);
}

.media-frame img {
    width: 100%;
    height: 100%;
    display: block;
    object-fit: contain;
    object-position: center;
}

.media-banner {
    max-height: 300px;
    height: min(300px, 48vw);
    min-height: 180px;
}

.media-card {
    height: 205px;
}

.media-wide {
    height: 240px;
}

.media-tall {
    width: min(100%, 320px);
    height: 420px;
    margin: 0 auto;
}

.media-icon {
    width: 72px;
    height: 72px;
    border-radius: 16px;
}

.banner-copy {
    max-width: 860px;
    margin-top: 22px;
}

.banner-copy .brand-kicker {
    color: var(--brand);
    font-weight: 900;
    letter-spacing: 0.09em;
}

.signature-line {
    margin: 5px 0 12px;
    color: var(--title);
    font-size: clamp(25px, 4vw, 34px);
    font-weight: 900;
    line-height: 1.25;
}

.tile-grid,
.three-grid,
.two-grid,
.six-grid,
.four-grid {
    display: grid;
    gap: 16px;
}

.tile-grid,
.three-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.two-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.four-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
}

.six-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.info-card,
.tile,
.shelf-cell,
.topic-cell,
.statement-card,
.term-card,
.qa-card,
.directory-row,
.step-card {
    min-width: 0;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: #fff;
    box-shadow: var(--shadow);
}

.info-card,
.tile,
.topic-cell,
.statement-card,
.term-card,
.qa-card,
.step-card {
    padding: 22px;
}

.tile .tile-mark {
    width: 46px;
    height: 8px;
    margin-bottom: 18px;
    border-radius: 3px;
    background: var(--brand-bright);
}

.tile:nth-child(even) .tile-mark {
    background: var(--brand-deep);
}

.tile p,
.info-card p,
.topic-cell p,
.statement-card p,
.term-card p,
.qa-card p,
.step-card p {
    color: var(--muted);
}

.tile a,
.info-card a,
.topic-cell a,
.shelf-cell a {
    font-weight: 800;
}

.split-section {
    display: grid;
    grid-template-columns: minmax(280px, 0.85fr) minmax(0, 1.15fr);
    gap: 28px;
    align-items: center;
}

.split-section.reverse {
    grid-template-columns: minmax(0, 1.15fr) minmax(280px, 0.85fr);
}

.number-list {
    display: grid;
    gap: 0;
    border-top: 1px solid var(--border);
}

.number-item {
    display: grid;
    grid-template-columns: 64px minmax(0, 1fr) auto;
    gap: 16px;
    align-items: center;
    padding: 18px 0;
    border-bottom: 1px solid var(--border);
}

.number-item .num {
    color: var(--brand);
    font-size: 27px;
    font-weight: 900;
    line-height: 1;
}

.number-item p {
    margin: 4px 0 0;
    color: var(--muted);
}

.number-item a {
    font-weight: 800;
    white-space: nowrap;
}

.catalog-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 14px;
}

.catalog-chip {
    min-height: 122px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    padding: 18px;
    border: 1px solid var(--border);
    border-radius: 12px;
    background: var(--bg-deep);
}

.catalog-chip strong {
    color: var(--title);
    font-size: 18px;
}

.catalog-chip span {
    color: var(--muted);
    font-size: 14px;
}

.shelf-list {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    border-top: 1px solid var(--border);
    border-left: 1px solid var(--border);
}

.shelf-cell {
    min-height: 144px;
    padding: 20px;
    border-radius: 0;
    border-top: 0;
    border-left: 0;
    box-shadow: none;
}

.shelf-cell small,
.timeline-item small,
.note-meta {
    display: block;
    margin-bottom: 6px;
    color: var(--subtle);
    font-weight: 700;
}

.big-rank-list {
    display: grid;
    gap: 14px;
}

.big-rank {
    display: grid;
    grid-template-columns: 92px minmax(0, 1fr);
    gap: 18px;
    align-items: start;
    padding: 22px 0;
    border-bottom: 1px solid var(--border);
}

.big-rank-number {
    color: var(--brand);
    font-size: 46px;
    font-weight: 900;
    line-height: 1;
    letter-spacing: -0.05em;
}

.timeline {
    position: relative;
    margin-left: 12px;
    padding-left: 28px;
    border-left: 2px solid rgba(0, 51, 160, 0.2);
}

.timeline-item {
    position: relative;
    padding: 4px 0 28px;
}

.timeline-item::before {
    content: "";
    position: absolute;
    left: -36px;
    top: 10px;
    width: 14px;
    height: 14px;
    border: 3px solid #fff;
    border-radius: 50%;
    background: var(--brand);
    box-shadow: 0 0 0 2px rgba(0, 51, 160, 0.16);
}

.timeline-status {
    display: inline-flex;
    align-items: center;
    min-height: 30px;
    padding: 4px 10px;
    border-radius: 8px;
    background: var(--bg-soft);
    color: var(--brand);
    font-size: 13px;
    font-weight: 900;
}

.long-strip-list {
    display: grid;
    gap: 12px;
}

.long-strip {
    display: grid;
    grid-template-columns: 130px minmax(0, 1fr);
    gap: 18px;
    padding: 18px 20px;
    border: 1px solid var(--border);
    border-radius: 12px;
    background: #fff;
}

.long-strip strong {
    color: var(--brand-deep);
}

.steps {
    counter-reset: steps;
    display: grid;
    gap: 14px;
}

.step-card {
    position: relative;
    padding-left: 82px;
}

.step-card::before {
    counter-increment: steps;
    content: counter(steps, decimal-leading-zero);
    position: absolute;
    left: 20px;
    top: 21px;
    color: var(--brand);
    font-size: 28px;
    font-weight: 900;
}

.editor-note {
    padding: 22px;
    border-left: 4px solid var(--brand);
    background: var(--bg-deep);
    border-radius: 0 12px 12px 0;
}

.editor-note strong {
    color: var(--brand-deep);
}

.article-copy {
    max-width: 850px;
}

.article-copy h2 {
    margin-top: 34px;
}

.article-copy p {
    color: var(--text);
    line-height: 1.95;
}

.term-list {
    display: grid;
    gap: 16px;
}

.term-card h2,
.qa-card h2 {
    font-size: 20px;
}

.qa-list {
    display: grid;
    gap: 14px;
}

.app-product-grid {
    display: grid;
    grid-template-columns: minmax(250px, 0.8fr) minmax(0, 1.2fr);
    gap: 34px;
    align-items: center;
}

.app-icon-row {
    display: flex;
    align-items: center;
    gap: 14px;
    margin: 18px 0;
}

.app-icon-row .media-frame {
    flex: 0 0 72px;
}

.app-icon-row strong {
    display: block;
    color: var(--title);
    font-size: 18px;
}

.app-icon-row span {
    color: var(--muted);
}

.site-footer {
    background: #0A1628;
    color: #A0AEC0;
    padding: 42px 0 calc(28px + env(safe-area-inset-bottom));
}

.footer-brand-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 28px;
    padding-bottom: 28px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.12);
}

.footer-brand-row p {
    max-width: 590px;
    margin: 0;
    color: #CBD5E0;
}

.footer-brand {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    color: #fff;
}

.brand-logo-footer {
    height: 32px;
    max-width: 150px;
    object-fit: contain;
}

.footer-brand strong,
.footer-brand small {
    display: block;
    color: #fff;
}

.footer-brand strong {
    font-size: 20px;
}

.footer-brand small {
    color: #A0AEC0;
}

.footer-groups {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 28px;
    padding: 30px 0;
}

.footer-groups h2 {
    color: #fff;
    font-size: 15px;
    margin-bottom: 10px;
}

.footer-groups a {
    display: block;
    padding: 4px 0;
    color: #CBD5E0;
    font-size: 14px;
}

.footer-groups a:hover {
    color: #fff;
}

.footer-notice {
    display: flex;
    justify-content: space-between;
    gap: 24px;
    padding-top: 22px;
    border-top: 1px solid rgba(255, 255, 255, 0.12);
    color: #A0AEC0;
    font-size: 13px;
}

.footer-notice p {
    margin: 0;
}

.site-overlay {
    position: fixed;
    inset: 0;
    z-index: 1210;
    visibility: hidden;
    pointer-events: none;
    opacity: 0;
    background: rgba(10, 22, 40, 0.46);
    transition: opacity 0.18s ease, visibility 0.18s ease;
}

.site-overlay.is-active {
    visibility: visible;
    pointer-events: auto;
    opacity: 1;
}

.catalog-panel,
.search-layer {
    position: fixed;
    z-index: 1220;
    visibility: hidden;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.16s ease, visibility 0.16s ease, transform 0.16s ease;
}

.catalog-panel {
    top: calc(var(--topline-h) + var(--masthead-h));
    left: 0;
    right: 0;
    max-height: calc(100vh - var(--topline-h) - var(--masthead-h));
    overflow-y: auto;
    transform: translateY(-10px);
    background: #fff;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 24px 50px rgba(10, 22, 40, 0.18);
}

.catalog-panel.is-open,
.search-layer.is-open {
    visibility: visible;
    pointer-events: auto;
    opacity: 1;
    transform: translateY(0);
}

.catalog-inner {
    padding-top: 20px;
    padding-bottom: 26px;
}

.panel-head,
.search-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 18px;
    margin-bottom: 18px;
}

.panel-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--title);
    font-weight: 900;
}

.panel-close {
    border: 1px solid var(--border);
    background: #fff;
    color: var(--brand);
    cursor: pointer;
}

.catalog-groups {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 20px;
}

.catalog-groups h2 {
    margin-bottom: 10px;
    font-size: 16px;
}

.catalog-groups a {
    display: block;
    min-height: 66px;
    padding: 10px 0;
    border-top: 1px solid var(--border);
}

.catalog-groups strong,
.catalog-groups span {
    display: block;
}

.catalog-groups strong {
    color: var(--title);
}

.catalog-groups span {
    margin-top: 2px;
    color: var(--muted);
    font-size: 13px;
    line-height: 1.55;
}

.search-layer {
    top: calc(var(--topline-h) + var(--masthead-h));
    left: 0;
    right: 0;
    transform: translateY(-8px);
}

.search-card {
    width: min(760px, calc(100% - 32px));
    margin: 12px auto 0;
    padding: 24px;
    border: 1px solid var(--border);
    border-radius: 14px;
    background: #fff;
    box-shadow: 0 24px 50px rgba(10, 22, 40, 0.18);
}

.search-head h2 {
    margin: 0;
    font-size: 22px;
}

.search-appearance {
    display: block;
}

.search-appearance span {
    display: block;
    margin-bottom: 7px;
    color: var(--muted);
    font-size: 14px;
    font-weight: 800;
}

.search-appearance input {
    width: 100%;
    min-height: 48px;
    padding: 10px 13px;
    border: 1px solid rgba(0, 51, 160, 0.25);
    border-radius: 10px;
    background: #fff;
    color: var(--title);
}

.search-presets {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px;
    margin-top: 16px;
}

.search-presets a {
    min-height: 46px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--bg-deep);
    font-weight: 800;
}

.search-presets a[hidden] {
    display: none;
}

.search-note {
    margin: 14px 0 0;
    color: var(--subtle);
    font-size: 13px;
}

.mobile-bottom-nav {
    display: none;
}

@media (max-width: 980px) {
    .page-hero-grid,
    .split-section,
    .split-section.reverse,
    .app-product-grid {
        grid-template-columns: 1fr;
    }

    .tile-grid,
    .three-grid,
    .six-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .four-grid,
    .catalog-grid,
    .catalog-groups {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .media-tall {
        height: 380px;
    }
}

@media (max-width: 720px) {
    :root {
        --fixed-h: 90px;
    }

    .site-width {
        width: min(100% - 32px, 1220px);
    }

    .tab-strip {
        display: none;
    }

    main {
        padding-top: var(--fixed-h);
    }

    .masthead-inner {
        grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
        gap: 8px;
    }

    .masthead-logo {
        min-width: 0;
    }

    .brand-logo {
        max-width: 108px;
        height: 30px;
    }

    .catalog-button,
    .app-link {
        padding-left: 12px;
        padding-right: 12px;
        font-size: 14px;
    }

    .app-link {
        white-space: nowrap;
    }

    .page-wrap {
        padding: 30px 0 62px;
    }

    .page-hero {
        padding: 26px 0 22px;
    }

    .content-section {
        padding: 32px 0;
    }

    .section-head,
    .footer-brand-row,
    .footer-notice {
        align-items: flex-start;
        flex-direction: column;
    }

    .tile-grid,
    .three-grid,
    .two-grid,
    .four-grid,
    .six-grid,
    .catalog-grid,
    .footer-groups,
    .catalog-groups,
    .shelf-list {
        grid-template-columns: 1fr;
    }

    .number-item {
        grid-template-columns: 52px minmax(0, 1fr);
    }

    .number-item a {
        grid-column: 2;
        justify-self: start;
    }

    .big-rank {
        grid-template-columns: 70px minmax(0, 1fr);
    }

    .big-rank-number {
        font-size: 38px;
    }

    .long-strip {
        grid-template-columns: 1fr;
        gap: 6px;
    }

    .media-banner {
        height: 220px;
        min-height: 160px;
    }

    .media-card,
    .media-wide {
        height: 200px;
    }

    .catalog-panel {
        top: calc(var(--topline-h) + var(--masthead-h));
        width: 100%;
        max-height: calc(100vh - var(--topline-h) - var(--masthead-h));
    }

    .catalog-inner {
        width: 100%;
        padding-left: 16px;
        padding-right: 16px;
    }

    .search-layer {
        top: calc(var(--topline-h) + var(--masthead-h));
        bottom: 0;
        background: var(--bg-soft);
    }

    .search-card {
        width: 100%;
        height: 100%;
        margin: 0;
        padding: 22px 16px 80px;
        border: 0;
        border-radius: 0;
        overflow-y: auto;
        box-shadow: none;
    }

    .search-presets {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .mobile-bottom-nav {
        position: fixed;
        left: 0;
        right: 0;
        bottom: 0;
        z-index: 1180;
        min-height: calc(50px + env(safe-area-inset-bottom));
        display: grid;
        grid-template-columns: repeat(5, minmax(0, 1fr));
        padding-bottom: env(safe-area-inset-bottom);
        border-top: 1px solid var(--border);
        background: rgba(255, 255, 255, 0.98);
        box-shadow: 0 -10px 24px rgba(0, 33, 102, 0.08);
    }

    .mobile-bottom-nav a {
        min-width: 0;
        min-height: 50px;
        display: flex;
        align-items: center;
        justify-content: center;
        padding: 0 4px;
        color: var(--muted);
        font-size: 12px;
        font-weight: 800;
    }

    .mobile-bottom-nav a.is-current {
        background: var(--brand);
        color: #fff;
    }

    .site-footer {
        padding-bottom: calc(82px + env(safe-area-inset-bottom));
    }

    .site-overlay {
        z-index: 1210;
    }
}

@media (max-width: 420px) {
    .site-width {
        width: calc(100% - 32px);
    }

    .blue-line-inner {
        font-size: 11px;
    }

    .brand-wordmark {
        font-size: 24px;
    }

    .catalog-button,
    .app-link {
        min-width: 64px;
        padding-left: 9px;
        padding-right: 9px;
    }

    .media-banner {
        height: 190px;
    }

    .info-card,
    .tile,
    .topic-cell,
    .statement-card,
    .term-card,
    .qa-card,
    .step-card {
        padding: 18px;
    }

    .step-card {
        padding-left: 68px;
    }

    .step-card::before {
        left: 16px;
        font-size: 24px;
    }
}