/* ============================================================
   china-blue-tech — 蓝白体育数据科技馆设计系统
   白底 / #2563eb 主蓝 / #f2f6fb 浅蓝灰底 / 深灰 #1f2937
   小圆角 6、细分隔线、数据面板、直边卡片
   ============================================================ */

:root {
    --bt-ink: #1f2937;
    --bt-ink-soft: #5b6c80;
    --bt-blue: #2563eb;
    --bt-blue-deep: #1d4ed8;
    --bt-blue-soft: #eaf1fc;
    --bt-blue-faint: #f5f9fe;
    --bt-line: #d9e4f2;
    --bt-line-soft: #e9f0f9;
    --bt-bg: #f2f6fb;
    --bt-panel: #ffffff;
    --bt-radius: 6px;
    --bt-shadow: 0 8px 22px rgba(31, 59, 110, 0.08);
    --bt-shadow-sm: 0 2px 8px rgba(31, 59, 110, 0.06);
    --bt-maxw: 1200px;
}

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

html {
    -webkit-text-size-adjust: 100%;
}

body {
    background: var(--bt-bg);
    color: var(--bt-ink);
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC",
        "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
    line-height: 1.7;
    font-size: 16px;
}

img {
    display: block;
    max-width: 100%;
    height: auto;
}

a {
    color: inherit;
    text-decoration: none;
}

ul,
ol,
dl {
    list-style: none;
}

button {
    font-family: inherit;
    background: none;
    border: 0;
    cursor: pointer;
}

/* ---------- 容器与通用文字 ---------- */

.bt-wrap {
    max-width: var(--bt-maxw);
    margin: 0 auto;
    padding-left: clamp(16px, 4vw, 32px);
    padding-right: clamp(16px, 4vw, 32px);
}

.bt-kicker {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--bt-blue);
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 2px;
}

.bt-kicker::before {
    content: "";
    width: 18px;
    height: 2px;
    background: var(--bt-blue);
    border-radius: 1px;
}

.bt-title {
    font-size: clamp(24px, 3.2vw, 34px);
    line-height: 1.3;
    letter-spacing: 0.4px;
    margin: 12px 0 14px;
}

.bt-lead {
    color: var(--bt-ink-soft);
    max-width: 46em;
}

/* ---------- 顶部导航（白底，选中蓝色下划线） ---------- */

.bt-head {
    position: sticky;
    top: 0;
    z-index: 60;
    background: var(--bt-panel);
    border-bottom: 1px solid var(--bt-line-soft);
    transition: box-shadow 0.2s ease;
}

.bt-head.is-scrolled {
    box-shadow: 0 4px 14px rgba(31, 59, 110, 0.07);
}

.bt-head-inner {
    display: flex;
    align-items: center;
    min-height: 64px;
    gap: 18px;
}

.bt-brand {
    font-size: 19px;
    font-weight: 800;
    letter-spacing: 0.2px;
    white-space: nowrap;
}

.bt-brand i {
    color: var(--bt-blue);
    margin-right: 8px;
}

.bt-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    background: var(--bt-panel);
    border-bottom: 1px solid var(--bt-line-soft);
    padding: 6px 0 12px;
    box-shadow: var(--bt-shadow-sm);
}

.bt-nav.open {
    display: block;
}

.bt-nav a {
    display: block;
    padding: 12px 24px;
    font-size: 15px;
    color: var(--bt-ink-soft);
    position: relative;
}

.bt-nav a.active {
    color: var(--bt-blue);
    font-weight: 600;
}

.bt-nav a:hover {
    color: var(--bt-blue);
}

.bt-head-cta {
    margin-left: auto;
}

.bt-burger {
    display: inline-flex;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 44px;
    height: 44px;
    padding: 0 10px;
}

.bt-burger span {
    display: block;
    height: 2px;
    border-radius: 1px;
    background: var(--bt-ink);
}

.bt-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 44px;
    padding: 0 22px;
    border-radius: var(--bt-radius);
    font-size: 15px;
    font-weight: 600;
    background: var(--bt-blue);
    color: #ffffff;
    transition: background 0.2s ease;
}

.bt-btn:hover {
    background: var(--bt-blue-deep);
}

.bt-btn-line {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 44px;
    padding: 0 22px;
    border-radius: var(--bt-radius);
    font-size: 15px;
    font-weight: 600;
    background: var(--bt-panel);
    color: var(--bt-blue);
    border: 1px solid var(--bt-line);
    transition: border-color 0.2s ease, color 0.2s ease;
}

.bt-btn-line:hover {
    border-color: var(--bt-blue);
}

.bt-btn-light {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 44px;
    padding: 0 24px;
    border-radius: var(--bt-radius);
    font-size: 15px;
    font-weight: 600;
    background: #ffffff;
    color: var(--bt-blue-deep);
}

/* ---------- Hero（数据面板叠卡） ---------- */

.bt-hero {
    background:
        linear-gradient(to right, rgba(37, 99, 235, 0.035) 1px, transparent 1px),
        linear-gradient(to bottom, rgba(37, 99, 235, 0.035) 1px, transparent 1px),
        var(--bt-panel);
    background-size: 46px 46px;
    border-bottom: 1px solid var(--bt-line-soft);
    padding: clamp(34px, 6vw, 72px) 0 clamp(44px, 6vw, 78px);
}

.bt-hero-grid {
    display: grid;
    gap: clamp(28px, 5vw, 60px);
    align-items: center;
}

.bt-hero h2 {
    font-size: clamp(30px, 4.6vw, 52px);
    line-height: 1.18;
    letter-spacing: 0.5px;
    font-weight: 800;
}

.bt-hero .bt-lead {
    margin-top: 18px;
    font-size: 16px;
}

.bt-hero .bt-lead + .bt-lead {
    margin-top: 10px;
}

.bt-metric {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 26px;
    margin-top: 22px;
    padding-top: 16px;
    border-top: 1px dashed var(--bt-line);
    color: var(--bt-ink-soft);
    font-size: 13px;
}

.bt-metric b {
    color: var(--bt-blue-deep);
    font-weight: 700;
}

.bt-cta-row {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    margin-top: 26px;
}

.mobile-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 24px;
}

.mobile-topics span {
    padding: 6px 14px;
    border: 1px solid #d3e2f8;
    border-radius: 999px;
    background: var(--bt-blue-faint);
    color: var(--bt-blue-deep);
    font-size: 13px;
}

.bt-hero-media {
    position: relative;
    margin-bottom: 26px;
}

.bt-frame {
    overflow: hidden;
    border-radius: var(--bt-radius);
    background: var(--bt-blue-soft);
}

.bt-frame img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.bt-frame-hero {
    aspect-ratio: 16 / 9;
}

.bt-frame-169 {
    aspect-ratio: 16 / 9;
}

.bt-frame-43 {
    aspect-ratio: 4 / 3;
}

.bt-frame-tall {
    aspect-ratio: 3 / 4;
}

.bt-data-panel {
    position: absolute;
    left: 14px;
    bottom: -34px;
    width: min(360px, 74%);
    background: var(--bt-panel);
    border-radius: var(--bt-radius);
    border-top: 3px solid var(--bt-blue);
    box-shadow: var(--bt-shadow);
    padding: 14px 18px 10px;
    z-index: 2;
}

.bt-dlrows > div {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    align-items: baseline;
    padding: 7px 0;
    border-bottom: 1px dashed var(--bt-line-soft);
}

.bt-dlrows > div:last-child {
    border-bottom: 0;
    padding-bottom: 2px;
}

.bt-dlrows dt {
    font-size: 12px;
    color: var(--bt-ink-soft);
}

.bt-dlrows dd {
    text-align: right;
    font-size: 13px;
    font-weight: 600;
    font-variant-numeric: tabular-nums;
}

.bt-dlrows .row-total {
    border-top: 1px dashed var(--bt-line);
    margin-top: 2px;
}

.bt-caption {
    font-size: 12px;
    color: var(--bt-ink-soft);
    margin-top: 8px;
}

/* ---------- 内容分区 ---------- */

.bt-sec {
    padding: clamp(44px, 6.4vw, 84px) 0;
}

.bt-sec-tint {
    background: var(--bt-panel);
    border-top: 1px solid var(--bt-line-soft);
    border-bottom: 1px solid var(--bt-line-soft);
}

.bt-sec-head {
    margin-bottom: clamp(24px, 3.4vw, 40px);
    max-width: 54em;
}

.bt-sec-head p {
    margin-top: 6px;
    color: var(--bt-ink-soft);
}

/* ---------- 统计信息卡（仅界面示例指标） ---------- */

.bt-stats {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
}

.bt-stat {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-top: 3px solid var(--bt-blue);
    border-radius: var(--bt-radius);
    padding: 18px 16px;
}

.bt-stat b {
    display: block;
    font-size: clamp(26px, 3vw, 34px);
    font-weight: 800;
    line-height: 1.1;
    font-variant-numeric: tabular-nums;
    letter-spacing: 0.3px;
}

.bt-stat span {
    display: block;
    margin-top: 6px;
    font-size: 14px;
    font-weight: 600;
    color: var(--bt-ink);
}

.bt-stat small {
    display: block;
    margin-top: 4px;
    color: var(--bt-ink-soft);
    font-size: 12px;
}

/* ---------- 两列横功能卡 ---------- */

.bt-func-grid {
    display: grid;
    gap: 22px;
}

.bt-func-card {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    overflow: hidden;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
}

.bt-func-card figure {
    min-height: 0;
}

.bt-func-card .bt-frame {
    border-radius: 0;
    height: 100%;
}

.bt-func-card .bt-frame-169 {
    aspect-ratio: 16 / 9;
}

.bt-func-body {
    padding: 24px 24px 26px;
}

.bt-func-body h4 {
    font-size: 20px;
    margin-bottom: 10px;
}

.bt-func-body p {
    color: var(--bt-ink-soft);
    margin-bottom: 10px;
}

.bt-func-body p:last-child {
    margin-bottom: 0;
}

/* ---------- 两列功能卡（deck） ---------- */

.bt-deck {
    display: grid;
    gap: 18px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-deck-card {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    padding: 24px 22px;
    display: grid;
    gap: 12px;
    align-content: start;
}

.bt-deck-card h4 {
    display: flex;
    align-items: baseline;
    gap: 10px;
    font-size: 18px;
}

.bt-deck-card h4::before {
    content: "";
    align-self: center;
    width: 10px;
    height: 10px;
    flex: none;
    background: var(--bt-blue);
    border-radius: 2px;
}

.bt-deck-card p {
    color: var(--bt-ink-soft);
    font-size: 15px;
}

.bt-dots {
    display: grid;
    gap: 6px;
    color: var(--bt-ink-soft);
    font-size: 14px;
}

.bt-dots li {
    position: relative;
    padding-left: 16px;
}

.bt-dots li::before {
    content: "";
    position: absolute;
    left: 2px;
    top: 0.72em;
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: #9db9e8;
}

/* ---------- 多端版本卡 ---------- */

.bt-ver-grid {
    display: grid;
    gap: 18px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-ver-card {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    overflow: hidden;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
}

.bt-ver-screen {
    height: 116px;
    border-bottom: 1px solid var(--bt-line-soft);
    background:
        linear-gradient(90deg, rgba(37, 99, 235, 0.09) 12px, transparent 12px) 16px 24px / 180px 1px no-repeat,
        linear-gradient(90deg, rgba(37, 99, 235, 0.07) 90px, transparent 90px) 16px 38px / 300px 1px no-repeat,
        linear-gradient(90deg, rgba(37, 99, 235, 0.12) 20px, transparent 20px) 16px 58px / 60px 60px no-repeat,
        rgba(37, 99, 235, 0.05);
    border-radius: var(--bt-radius) var(--bt-radius) 0 0;
    position: relative;
}

.bt-ver-screen::before {
    content: "";
    position: absolute;
    top: 10px;
    left: 14px;
    width: 44px;
    height: 8px;
    border-radius: 999px;
    background: rgba(37, 99, 235, 0.25);
}

.bt-ver-body {
    padding: 20px 22px 24px;
}

.bt-ver-body h4 {
    font-size: 18px;
    margin-bottom: 8px;
}

.bt-ver-body p {
    color: var(--bt-ink-soft);
    font-size: 15px;
}

.bt-ver-body .bt-tag-row {
    margin-top: 14px;
}

.bt-tag-row {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.bt-tag-row span {
    font-size: 12px;
    color: var(--bt-blue-deep);
    background: var(--bt-blue-faint);
    border: 1px solid var(--bt-line);
    padding: 3px 10px;
    border-radius: 999px;
}

/* ---------- 数据体验区 dl 块 ---------- */

.bt-lab-grid {
    display: grid;
    gap: 22px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-lab-dl {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    padding: 8px 22px;
}

.bt-lab-dl > div {
    display: grid;
    gap: 0 18px;
    padding: 16px 0;
    border-bottom: 1px dashed var(--bt-line-soft);
}

.bt-lab-dl > div:last-child {
    border-bottom: 0;
}

.bt-lab-dl dt {
    font-size: 15px;
    font-weight: 600;
}

.bt-lab-dl dd {
    color: var(--bt-ink-soft);
    font-size: 14px;
    margin-top: 4px;
}

.bt-note {
    display: grid;
    gap: 8px;
    margin-top: 18px;
}

.bt-note li {
    position: relative;
    padding-left: 18px;
    color: var(--bt-ink-soft);
    font-size: 13px;
}

.bt-note li::before {
    content: "·";
    position: absolute;
    left: 2px;
    top: 0;
    color: var(--bt-blue);
    font-weight: 800;
}

.bt-topic-card {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-left: 4px solid var(--bt-blue);
    border-radius: var(--bt-radius);
    padding: 24px 24px 22px;
    display: grid;
    align-content: start;
    gap: 10px;
}

.bt-topic-card h4 {
    font-size: 19px;
}

.bt-topic-card p {
    color: var(--bt-ink-soft);
    font-size: 15px;
}

/* ---------- 活动任务条 ---------- */

.bt-event-grid {
    display: grid;
    gap: 24px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-event-grid > figure {
    min-height: 0;
}

.bt-task-list {
    display: grid;
}

.bt-task {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    gap: 16px;
    padding: 16px 2px;
    border-top: 1px solid var(--bt-line-soft);
    align-items: baseline;
}

.bt-task:first-child {
    border-top: 0;
    padding-top: 4px;
}

.bt-task-tag {
    font-size: 12px;
    font-weight: 700;
    color: var(--bt-blue);
    background: var(--bt-blue-faint);
    border: 1px solid var(--bt-line);
    border-radius: 999px;
    padding: 4px 12px;
    white-space: nowrap;
    align-self: center;
}

.bt-task p {
    color: var(--bt-ink-soft);
    font-size: 15px;
}

.bt-task b {
    color: var(--bt-ink);
}

/* ---------- 评价与 FAQ ---------- */

.bt-voices {
    display: grid;
    gap: 18px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-voice {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    padding: 22px 22px 18px;
}

.bt-voice p {
    color: var(--bt-ink);
    font-size: 15px;
}

.bt-voice-meta {
    margin-top: 12px;
    font-size: 12px;
    color: var(--bt-ink-soft);
    border-top: 1px dashed var(--bt-line-soft);
    padding-top: 10px;
}

.bt-faq-list {
    display: grid;
    gap: 12px;
    max-width: 900px;
}

details.bt-faq-item {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-left: 3px solid var(--bt-blue);
    border-radius: var(--bt-radius);
    padding: 0;
}

details.bt-faq-item summary {
    cursor: pointer;
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 15px 20px;
    font-weight: 600;
    font-size: 15px;
}

details.bt-faq-item summary::-webkit-details-marker {
    display: none;
}

details.bt-faq-item summary::after {
    content: "+";
    flex: none;
    font-size: 20px;
    font-weight: 400;
    color: var(--bt-blue);
    line-height: 1;
}

details.bt-faq-item[open] summary::after {
    content: "−";
}

details.bt-faq-item p {
    padding: 0 20px 16px;
    color: var(--bt-ink-soft);
    font-size: 14px;
}

/* ---------- 蓝色收尾 CTA ---------- */

.bt-final-cta {
    background:
        linear-gradient(105deg, rgba(255, 255, 255, 0.06), transparent 40%),
        var(--bt-blue);
    color: #ffffff;
    border-radius: 10px;
    padding: clamp(30px, 5vw, 52px) clamp(20px, 4vw, 56px);
    display: grid;
    gap: 16px;
    justify-items: start;
}

.bt-final-cta h3 {
    font-size: clamp(22px, 3vw, 30px);
    letter-spacing: 0.4px;
}

.bt-final-cta p {
    color: #dbe7ff;
    font-size: 14px;
}

/* ---------- 内页页头 ---------- */

.bt-pagehead {
    background:
        linear-gradient(to right, rgba(37, 99, 235, 0.04) 1px, transparent 1px),
        linear-gradient(to bottom, rgba(37, 99, 235, 0.04) 1px, transparent 1px),
        var(--bt-panel);
    background-size: 46px 46px;
    border-bottom: 1px solid var(--bt-line-soft);
    padding: clamp(30px, 5vw, 54px) 0;
}

.bt-pagehead h2 {
    font-size: clamp(26px, 3.8vw, 40px);
    letter-spacing: 0.4px;
    line-height: 1.25;
    margin-top: 10px;
}

.bt-pagehead .bt-lead {
    margin-top: 12px;
    max-width: 42em;
}

/* ---------- About 实验室区段 ---------- */

.bt-lab-unit {
    display: grid;
    gap: 22px;
    grid-template-columns: minmax(0, 1fr);
    padding: clamp(26px, 4vw, 44px) 0;
    border-top: 1px solid var(--bt-line-soft);
}

.bt-lab-unit:first-of-type {
    border-top: 0;
}

.bt-lab-copy h3 {
    font-size: 21px;
    margin-bottom: 10px;
}

.bt-lab-copy p {
    color: var(--bt-ink-soft);
    font-size: 15px;
    margin-bottom: 10px;
}

.bt-principles {
    display: grid;
    gap: 10px;
    margin-top: 4px;
}

.bt-principles li {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    gap: 12px;
    align-items: baseline;
    border-bottom: 1px dashed var(--bt-line-soft);
    padding: 8px 0;
}

.bt-principles li b {
    color: var(--bt-blue);
    font-size: 13px;
    white-space: nowrap;
}

.bt-principles li span {
    color: var(--bt-ink-soft);
    font-size: 14px;
}

.bt-swatch {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 14px;
}

.bt-swatch i {
    display: inline-flex;
    flex-direction: column;
    gap: 4px;
    font-style: normal;
    font-size: 12px;
    color: var(--bt-ink-soft);
}

.bt-swatch i em {
    display: block;
    width: 72px;
    height: 44px;
    border-radius: var(--bt-radius);
    border: 1px solid var(--bt-line);
    font-style: normal;
}

/* ---------- Product 行卡 deck ---------- */

.bt-prod-row {
    display: grid;
    gap: 18px;
}

.bt-prod-card {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    overflow: hidden;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
}

.bt-prod-card .bt-frame {
    border-radius: 0;
    height: 100%;
}

.bt-prod-body {
    padding: 20px 22px 22px;
}

.bt-prod-body h4 {
    font-size: 19px;
    margin-bottom: 10px;
}

.bt-prod-body .bt-dots {
    margin-top: 4px;
}

.bt-steps {
    display: grid;
    gap: 16px;
    margin-top: 18px;
    counter-reset: btstep;
}

.bt-steps li {
    position: relative;
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    padding: 18px 20px 18px 78px;
    counter-increment: btstep;
}

.bt-steps li::before {
    content: counter(btstep);
    position: absolute;
    left: 18px;
    top: 16px;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--bt-radius);
    background: var(--bt-blue);
    color: #ffffff;
    font-weight: 800;
    font-size: 18px;
}

.bt-steps b {
    display: block;
    margin-bottom: 4px;
}

.bt-steps p {
    color: var(--bt-ink-soft);
    font-size: 14px;
}

/* ---------- News 时间轴行 ---------- */

.bt-news-layout {
    display: grid;
    gap: 30px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-news-rail {
    position: relative;
    margin-left: 10px;
    padding-left: 28px;
}

.bt-news-rail::before {
    content: "";
    position: absolute;
    left: 0;
    top: 8px;
    bottom: 8px;
    width: 1px;
    background: var(--bt-line);
}

.bt-news-row {
    position: relative;
    padding: 18px 0;
    border-bottom: 1px dashed var(--bt-line-soft);
}

.bt-news-row::before {
    content: "";
    position: absolute;
    left: -33px;
    top: 26px;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    border: 2px solid var(--bt-blue);
    background: var(--bt-bg);
}

.bt-news-row time {
    display: inline-block;
    font-size: 12px;
    color: var(--bt-blue-deep);
    background: var(--bt-blue-faint);
    border: 1px solid var(--bt-line);
    border-radius: 999px;
    padding: 2px 10px;
    font-variant-numeric: tabular-nums;
}

.bt-news-row h3 {
    font-size: 18px;
    margin: 10px 0 6px;
}

.bt-news-row p {
    color: var(--bt-ink-soft);
    font-size: 14px;
    max-width: 56em;
}

.bt-aside {
    display: grid;
    align-content: start;
    gap: 18px;
}

.bt-aside-card {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-left: 3px solid var(--bt-blue);
    border-radius: var(--bt-radius);
    padding: 18px 18px 16px;
}

.bt-aside-card h4 {
    font-size: 15px;
    margin-bottom: 10px;
}

.bt-aside-card .bt-dlrows dd {
    font-size: 12px;
}

.bt-aside-card .bt-dlrows dt {
    font-size: 12px;
}

.bt-aside-card p {
    font-size: 12px;
    color: var(--bt-ink-soft);
}

/* ---------- Contact 帮助页 ---------- */

.bt-search-box {
    display: flex;
    align-items: center;
    gap: 12px;
    background: var(--bt-panel);
    border: 1px solid var(--bt-blue);
    border-radius: var(--bt-radius);
    box-shadow: var(--bt-shadow-sm);
    padding: 8px 8px 8px 18px;
    max-width: 720px;
}

.bt-search-box i {
    color: var(--bt-blue);
}

.bt-search-box span {
    color: var(--bt-ink-soft);
    font-size: 14px;
    flex: 1;
}

.bt-search-box em {
    font-style: normal;
    background: var(--bt-blue-soft);
    color: var(--bt-blue-deep);
    font-size: 13px;
    padding: 10px 18px;
    border-radius: var(--bt-radius);
    white-space: nowrap;
}

.bt-help-grid {
    display: grid;
    gap: 20px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-help-col h3 {
    display: flex;
    align-items: baseline;
    gap: 10px;
    font-size: 17px;
    margin-bottom: 14px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--bt-blue);
}

.bt-help-col h3 i {
    color: var(--bt-blue);
    font-style: normal;
}

.bt-help-col details {
    margin-bottom: 10px;
}

.bt-contact-fig {
    display: grid;
    gap: 18px;
    align-items: center;
}

.bt-contact-fig figure {
    min-height: 0;
}

/* ---------- Sports 体育中心 ---------- */

.bt-sched {
    display: grid;
}

.bt-sched-row {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 8px 20px;
    align-items: center;
    padding: 14px 2px;
    border-top: 1px dashed var(--bt-line);
    font-size: 15px;
}

.bt-sched-row:first-child {
    border-top: 0;
}

.bt-sched-row b {
    font-weight: 600;
}

.bt-sched-row time {
    color: var(--bt-ink-soft);
    font-size: 13px;
    font-variant-numeric: tabular-nums;
    text-align: right;
}

.bt-sched-row small {
    grid-column: 1 / 3;
    color: var(--bt-ink-soft);
    font-size: 12px;
}

.bt-channel-grid {
    display: grid;
    gap: 20px;
    grid-template-columns: minmax(0, 1fr);
}

.bt-channel {
    background: var(--bt-panel);
    border: 1px solid var(--bt-line);
    border-radius: var(--bt-radius);
    overflow: hidden;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
}

.bt-channel .bt-frame {
    border-radius: 0;
    height: 100%;
}

.bt-channel-body {
    padding: 22px 22px 24px;
}

.bt-channel-body h4 {
    font-size: 19px;
    margin-bottom: 8px;
}

.bt-channel-body p {
    color: var(--bt-ink-soft);
    font-size: 14px;
    margin-bottom: 10px;
}

/* ---------- 页脚 ---------- */

.bt-foot {
    background: var(--bt-panel);
    border-top: 2px solid var(--bt-blue);
    margin-top: clamp(30px, 4vw, 56px);
}

.bt-foot-grid {
    display: grid;
    gap: 28px;
    grid-template-columns: minmax(0, 1fr);
    padding: clamp(30px, 4vw, 48px) 0 30px;
}

.bt-foot-col h4 {
    font-size: 14px;
    letter-spacing: 1px;
    margin-bottom: 14px;
    color: var(--bt-ink);
}

.bt-foot-brand {
    display: inline-block;
    font-size: 18px;
    font-weight: 800;
    margin-bottom: 10px;
}

.bt-foot-col p {
    color: var(--bt-ink-soft);
    font-size: 13px;
    max-width: 24em;
}

.bt-foot-col ul {
    display: grid;
    gap: 8px;
}

.bt-foot-col a {
    color: var(--bt-ink-soft);
    font-size: 14px;
}

.bt-foot-col a:hover {
    color: var(--bt-blue);
}

.bt-foot-bottom {
    border-top: 1px solid var(--bt-line-soft);
    padding: 16px 0 22px;
    color: var(--bt-ink-soft);
    font-size: 12px;
    display: grid;
    gap: 6px;
}

/* ---------- 断点：≥768 ---------- */

@media (min-width: 768px) {
    .bt-stats {
        grid-template-columns: repeat(4, minmax(0, 1fr));
    }

    .bt-func-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        align-items: stretch;
    }

    .bt-func-card {
        grid-template-columns: minmax(0, 1fr);
    }

    .bt-ver-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
        align-items: stretch;
    }

    .bt-lab-grid {
        grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
        align-items: stretch;
    }

    .bt-lab-dl dt {
        font-size: 14px;
    }

    .bt-voices {
        grid-template-columns: repeat(3, minmax(0, 1fr));
        align-items: stretch;
    }

    .bt-news-layout {
        grid-template-columns: minmax(0, 1fr) 300px;
        align-items: start;
    }

    .bt-help-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
        align-items: start;
    }

    .bt-contact-fig {
        grid-template-columns: minmax(0, 1fr) minmax(0, 1.2fr);
    }

    .bt-channel-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        align-items: stretch;
    }

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

    .bt-prod-card {
        grid-template-columns: 220px minmax(0, 1fr);
    }

    .bt-steps {
        grid-template-columns: repeat(3, minmax(0, 1fr));
        align-items: stretch;
    }

    .bt-lab-unit {
        grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
        align-items: center;
    }
}

/* ---------- 断点：≥1024（桌面导航与横卡） ---------- */

@media (min-width: 1024px) {
    .bt-hero-grid {
        grid-template-columns: minmax(0, 1fr) minmax(0, 1.06fr);
    }

    .bt-burger {
        display: none;
    }

    .bt-nav {
        display: flex;
        position: static;
        background: none;
        border: 0;
        box-shadow: none;
        padding: 0;
        gap: 2px;
    }

    .bt-nav a {
        display: block;
        padding: 22px 16px;
        font-size: 15px;
    }

    .bt-nav a::after {
        content: "";
        position: absolute;
        left: 14px;
        right: 14px;
        bottom: 0;
        height: 3px;
        border-radius: 2px 2px 0 0;
        background: var(--bt-blue);
        opacity: 0;
        transform: scaleX(0.6);
        transition: opacity 0.2s ease, transform 0.2s ease;
    }

    .bt-nav a.active::after {
        opacity: 1;
        transform: scaleX(1);
    }

    .bt-func-card {
        grid-template-columns: minmax(0, 42%) minmax(0, 1fr);
    }

    .bt-deck {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        align-items: stretch;
    }

    .bt-event-grid {
        grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
        align-items: center;
    }
}

@media (max-width: 1023px) {
    .bt-head-cta {
        display: none;
    }

    .bt-burger {
        flex: none;
        width: 44px;
    }
}

@media (max-width: 767px) {
    .bt-data-panel {
        position: static;
        width: 100%;
        margin-top: -18px;
        z-index: 3;
    }

    .bt-hero-media {
        margin-bottom: 0;
    }
}