/* ===== 资料库（pm-library）· 系列样式 =====
   基础令牌、页头页脚来自 ../style.css，这里只写本栏目特有的排版。
   两类页面共用：资源库首页、高性价比人生指南的目录页与详情页。 */

.bt-main {
    padding-top: 72px; /* 与 pm-know-data 一致 */
}

/* ===== 面包屑 ===== */
.bt-crumb {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
    font-size: 13px;
    color: #9a9a9a;
    margin-bottom: 40px;
}

.bt-crumb a {
    color: #6b6b6b;
}

.bt-crumb a:hover {
    color: #000;
}

/* ===== 页头 ===== */
.bt-hero {
    padding: 32px 0 40px;
}

.bt-eyebrow {
    font-family: var(--font-num);
    font-size: 12px;
    letter-spacing: 0.16em;
    color: #9a9a9a;
    margin: 0 0 16px;
}

.bt-hero-title {
    font-family: var(--font-display);
    font-size: clamp(38px, 6vw, 62px);
    font-weight: 700;
    line-height: 1.1;
    letter-spacing: 0.02em;
    color: #000;
    margin: 0 0 20px;
}

.bt-hero-sub {
    font-size: 17px;
    line-height: 1.85;
    color: #4a4a4a;
    max-width: 720px;
    margin: 0 0 32px;
}

.bt-hero-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 12px 36px;
    font-size: 13px;
    letter-spacing: 0.04em;
    color: #6b6b6b;
}

.bt-hero-meta strong {
    font-family: var(--font-num);
    font-size: 20px;
    font-weight: 400;
    color: #000;
    margin-right: 4px;
}

/* ===== 来源声明（醒目但不喧宾夺主） ===== */
.bt-source {
    padding: 0 0 8px;
}

.bt-source-box {
    max-width: none;
    padding: 22px 26px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-left: 3px solid #000;
    border-radius: var(--radius-md);
    font-size: 14px;
    line-height: 1.85;
    color: #4a4a4a;
}

.bt-source-title {
    font-family: var(--font-num);
    font-size: 12px;
    letter-spacing: 0.14em;
    color: #000;
    margin: 0 0 10px;
}

.bt-source-box p {
    margin: 0 0 8px;
}

.bt-source-box p:last-child {
    margin-bottom: 0;
}

.bt-source-box a {
    color: #000;
    border-bottom: 1px solid rgba(0, 0, 0, 0.25);
}

.bt-source-box a:hover {
    border-color: #000;
}

.bt-source-note {
    font-size: 13px;
    color: #7a7a7a;
}

.bt-source-box code {
    font-size: 12.5px;
    padding: 1px 5px;
    background: rgba(0, 0, 0, 0.05);
    border-radius: 3px;
}

/* ===== 目录页 ===== */
.bt-list {
    padding: 40px 0 96px;
}

.bt-toolbar {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 28px;
    padding-bottom: 18px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.bt-search {
    flex: 1;
    min-width: 0;
}

.bt-search input {
    width: 100%;
    max-width: 460px;
    padding: 10px 16px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.12);
    border-radius: 999px;
    font-family: inherit;
    font-size: 14px;
    color: #1a1a1a;
    outline: none;
    transition: border-color 0.18s ease;
}

.bt-search input:focus {
    border-color: #000;
}

.bt-count {
    font-family: var(--font-num);
    font-size: 12px;
    letter-spacing: 0.04em;
    color: #9a9a9a;
    white-space: nowrap;
}

.bt-empty {
    text-align: center;
    font-size: 15px;
    color: #6b6b6b;
    padding: 56px 0 0;
}

.bt-empty a {
    border-bottom: 1px solid rgba(0, 0, 0, 0.2);
}

/* 长文 */
.bt-docs {
    margin-top: 56px;
}

.bt-docs-title {
    font-family: var(--font-display);
    font-size: 22px;
    font-weight: 700;
    color: #000;
    margin: 0 0 18px;
}

/* ===== 高性价比人生指南 · 目录页：左侧锚点 + 一行一个卡片 ===== */
.bt-layout-book {
    grid-template-columns: 232px minmax(0, 1fr);
    gap: 48px;
}

.bt-side-book {
    display: flex;
    flex-direction: column;
    max-height: calc(100vh - 120px);
}

.bt-nav-book {
    flex: 1;
    overflow-y: auto;
    padding-right: 4px;
    gap: 8px;
    scrollbar-width: thin;
}

.bt-nav-ch {
    justify-content: flex-start;
    gap: 10px;
    padding: 13px 10px;
    font-size: 13.5px;
    line-height: 1.7;
    border-radius: var(--radius-sm);
    overflow: hidden;
}

/* 作者样式的 display:flex 会盖过 UA 的 [hidden]{display:none} */
.bt-nav-link[hidden] {
    display: none;
}

.bt-nav-ch b {
    flex: 0 0 1.9em;
    text-align: right;
    font-size: 11px;
    color: #b0b0b0;
}

/* 目录文字只占一行，超出省略（完整标题在 title 提示里） */
.bt-nav-ch span {
    flex: 1;
    min-width: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.bt-nav-ch.is-active b {
    color: rgba(255, 255, 255, 0.55);
}

/* 「长文」与章节分开一点 */
.bt-nav-sep {
    margin-top: 6px;
    padding-top: 12px;
    border-top: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: 0 0 var(--radius-sm) var(--radius-sm);
}

/* 单列卡片 */
.bt-book-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.bt-book-row {
    display: grid;
    grid-template-columns: 44px minmax(0, 1fr) auto;
    gap: 16px;
    align-items: start;
    padding: 20px 24px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: var(--radius-md);
    scroll-margin-top: 96px;
    transition: border-color 0.18s ease, box-shadow 0.18s ease, transform 0.18s ease;
}

.bt-book-row[hidden] {
    display: none;
}

.bt-book-row:hover {
    border-color: #000;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.05);
    transform: translateY(-1px);
}

.bt-book-no {
    font-family: var(--font-num);
    font-size: 12.5px;
    line-height: 1.9;
    color: #b0b0b0;
}

.bt-book-main {
    display: flex;
    flex-direction: column;
    gap: 6px;
    min-width: 0;
}

.bt-book-title {
    font-family: var(--font-display);
    font-size: 19px;
    font-weight: 600;
    line-height: 1.45;
    letter-spacing: 0.02em;
    color: #000;
    overflow-wrap: anywhere;
}

.bt-book-lead {
    font-size: 13.5px;
    line-height: 1.75;
    color: #6b6b6b;
    overflow-wrap: anywhere;
}

.bt-book-meta {
    text-align: right;
    font-size: 12px;
    line-height: 1.9;
    color: #9a9a9a;
    white-space: nowrap;
}

.bt-book-meta b {
    font-family: var(--font-num);
    font-size: 18px;
    font-weight: 400;
    color: #000;
    margin-right: 3px;
}

.bt-book-ev {
    display: block;
    font-size: 11.5px;
    letter-spacing: 0.02em;
    color: #b0b0b0;
}

.bt-book-doc .bt-book-no {
    color: #c0c0c0;
}

.bt-book-doc .bt-book-meta {
    align-self: center;
    font-size: 11.5px;
    color: #b0b0b0;
}

/* 移动端折叠目录 */
.bt-toc {
    display: none;
    margin-bottom: 16px;
    padding: 0 16px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: var(--radius-sm);
}

.bt-toc summary {
    padding: 14px 0;
    font-size: 13.5px;
    color: #4a4a4a;
    cursor: pointer;
    list-style: none;
}

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

.bt-toc summary::after {
    content: '+';
    float: right;
    font-family: var(--font-num);
    color: #9a9a9a;
}

.bt-toc[open] summary::after {
    content: '−';
}

.bt-toc-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 2px 8px;
    padding: 8px 0 14px;
    border-top: 1px solid rgba(0, 0, 0, 0.06);
}

.bt-toc-grid .bt-nav-link {
    font-size: 12.5px;
    padding: 6px 8px;
}

/* ===== 资源库首页：左侧目录 + 右侧内容 ===== */
.bt-layout {
    display: grid;
    grid-template-columns: 196px minmax(0, 1fr);
    gap: 56px;
    align-items: start;
}

/* 左侧目录（随滚动吸顶） */
.bt-side {
    position: sticky;
    top: 92px;
}

.bt-nav-title {
    font-family: var(--font-num);
    font-size: 11.5px;
    letter-spacing: 0.14em;
    color: #b0b0b0;
    margin: 0 0 8px;
    padding: 0 12px;
}

.bt-nav {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.bt-nav-link {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 9px 12px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    line-height: 1.5;
    color: #6b6b6b;
    transition: background 0.18s ease, color 0.18s ease;
}

.bt-nav-link b {
    flex: 0 0 auto;
    font-family: var(--font-num);
    font-size: 12px;
    font-weight: 400;
    color: #b0b0b0;
}

.bt-nav-link:hover {
    background: rgba(0, 0, 0, 0.045);
    color: #000;
}

.bt-nav-link.is-active {
    background: #000;
    color: #fff;
}

.bt-nav-link.is-active b {
    color: rgba(255, 255, 255, 0.6);
}

.bt-side-tip {
    margin: 18px 0 0;
    padding: 0 12px;
    font-size: 12px;
    line-height: 1.75;
    color: #b0b0b0;
}

.bt-side-tip b {
    font-weight: 600;
    color: #6b6b6b;
}

.bt-content {
    min-width: 0;
}

.bt-featured {
    scroll-margin-top: 88px;
}

.bt-featured + .bt-featured {
    margin-top: 18px;
}

/* ===== 资源库首页 ===== */
.bt-hub-feature {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 200px;
    gap: 32px;
    padding: 34px 34px 30px;
    background: #000;
    border-radius: var(--radius-md);
    color: #fff;
    transition: transform 0.22s ease, box-shadow 0.22s ease;
    overflow: hidden;
}

.bt-hub-feature:hover {
    transform: translateY(-3px);
    box-shadow: 0 18px 44px rgba(0, 0, 0, 0.18);
}

.bt-hub-tag {
    font-family: var(--font-num);
    font-size: 11.5px;
    letter-spacing: 0.14em;
    color: rgba(255, 255, 255, 0.55);
    margin: 0 0 12px;
}

.bt-hub-name {
    font-family: var(--font-display);
    font-size: clamp(26px, 3.4vw, 36px);
    font-weight: 700;
    letter-spacing: 0.02em;
    line-height: 1.25;
    margin: 0 0 12px;
    color: #fff;
}

.bt-hub-desc {
    font-size: 15px;
    line-height: 1.85;
    color: rgba(255, 255, 255, 0.78);
    margin: 0 0 20px;
}

.bt-hub-facts {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 26px;
    font-size: 13px;
    color: rgba(255, 255, 255, 0.6);
}

.bt-hub-facts b {
    font-family: var(--font-num);
    font-size: 18px;
    font-weight: 400;
    color: #fff;
    margin-right: 3px;
}

.bt-hub-cta {
    align-self: end;
    justify-self: end;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 11px 20px;
    border: 1px solid rgba(255, 255, 255, 0.5);
    border-radius: 999px;
    font-size: 13.5px;
    color: #fff;
    white-space: nowrap;
}

.bt-hub-feature:hover .bt-hub-cta {
    background: #fff;
    color: #000;
    border-color: #fff;
}

.bt-section {
    margin-top: 64px;
    scroll-margin-top: 88px;
}

.bt-section-head {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    justify-content: space-between;
    gap: 8px 16px;
    padding-bottom: 16px;
    margin-bottom: 24px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.bt-section-title {
    font-family: var(--font-display);
    font-size: 24px;
    font-weight: 700;
    color: #000;
    margin: 0;
}

.bt-section-note {
    font-size: 12.5px;
    color: #9a9a9a;
}

.bt-res-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(300px, 100%), 1fr));
    gap: 16px;
}

.bt-res {
    display: flex;
    flex-direction: column;
    padding: 24px 24px 20px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: var(--radius-md);
    transition: border-color 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease;
}

.bt-res:hover {
    border-color: #000;
    transform: translateY(-2px);
    box-shadow: 0 10px 28px rgba(0, 0, 0, 0.06);
}

.bt-res-top {
    display: flex;
    align-items: baseline;
    gap: 10px;
    margin-bottom: 10px;
}

.bt-res-name {
    font-family: var(--font-display);
    font-size: 18px;
    font-weight: 600;
    line-height: 1.45;
    color: #000;
    margin: 0;
}

.bt-res-lang {
    font-family: var(--font-num);
    font-size: 11px;
    letter-spacing: 0.08em;
    color: #b0b0b0;
    white-space: nowrap;
}

.bt-res-desc {
    font-size: 14px;
    line-height: 1.75;
    color: #5a5a5a;
    margin: 0 0 16px;
}

/* 长英文名、长许可名都不许把卡片撑破 */
.bt-res-name,
.bt-res-desc,
.bt-hub-name,
.bt-hub-desc {
    overflow-wrap: anywhere;
}

.bt-res-meta {
    margin-top: auto;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 6px 14px;
    padding-top: 14px;
    border-top: 1px dashed rgba(0, 0, 0, 0.1);
    font-size: 12.5px;
    line-height: 1.7;
    color: #8a8a8a;
}

.bt-res-meta b {
    font-weight: 600;
    color: #4a4a4a;
}

.bt-res-lic {
    padding: 2px 8px;
    border: 1px solid rgba(0, 0, 0, 0.12);
    border-radius: 999px;
    font-size: 11.5px;
    color: #6b6b6b;
}

.bt-res-link {
    margin-left: auto;
    color: #000;
    border-bottom: 1px solid rgba(0, 0, 0, 0.2);
    white-space: nowrap;
}

/* 收录原则 */
.bt-rules {
    max-width: 860px;
    padding: 26px 28px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: var(--radius-md);
    font-size: 14.5px;
    line-height: 1.9;
    color: #4a4a4a;
}

.bt-rules ol {
    margin: 0;
    padding-left: 1.4em;
}

.bt-rules li {
    margin-bottom: 8px;
    list-style: decimal;
}

.bt-rules li:last-child {
    margin-bottom: 0;
}

/* ===== 详情页 ===== */
.bt-issue {
    padding: 72px 0;
    border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.bt-issue-head {
    max-width: 820px;
}

.bt-issue-cat {
    font-family: var(--font-num);
    font-size: 12px;
    letter-spacing: 0.1em;
    color: #9a9a9a;
    margin: 0 0 14px;
}

.bt-title {
    font-family: var(--font-display);
    font-size: clamp(28px, 4vw, 40px);
    font-weight: 600;
    line-height: 1.35;
    letter-spacing: 0.02em;
    color: #000;
    margin: 0;
}

.bt-issue-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 22px;
    margin-top: 18px;
    font-size: 13px;
    color: #7a7a7a;
}

.bt-issue-meta b {
    font-family: var(--font-num);
    font-weight: 400;
    color: #000;
}

.bt-issue-meta a {
    border-bottom: 1px solid rgba(0, 0, 0, 0.2);
}

.bt-source-inline {
    max-width: 820px;
    margin-top: 26px;
    padding: 14px 18px;
    background: rgba(0, 0, 0, 0.035);
    border-radius: var(--radius-sm);
    font-size: 12.5px;
    line-height: 1.8;
    color: #6b6b6b;
}

.bt-source-inline p {
    margin: 0;
}

.bt-source-inline a {
    color: #000;
    border-bottom: 1px solid rgba(0, 0, 0, 0.2);
}

.bt-body {
    max-width: 780px;
    padding-top: 32px;
    font-size: 16.5px;
    line-height: 1.95;
    color: #1a1a1a;
    overflow-wrap: break-word;
}

.bt-body p {
    margin: 0 0 16px;
}

.bt-body a {
    color: #000;
    border-bottom: 1px solid rgba(0, 0, 0, 0.22);
    overflow-wrap: anywhere;
}

.bt-body a:hover {
    border-color: #000;
}

/* ===== 正文 + 右侧本篇目录 ===== */
.bt-doc-layout {
    display: grid;
    grid-template-columns: minmax(0, 780px) minmax(0, 1fr);
    gap: 40px;
    align-items: start;
}

.bt-rail {
    position: sticky;
    top: 124px;
    display: flex;
    flex-direction: column;
    max-height: calc(100vh - 160px);
    padding: 32px 0 0;
}

/* 作者样式的 display:flex 会盖过 UA 的 [hidden]{display:none} */
.bt-rail[hidden] {
    display: none;
}

.bt-rail-title {
    flex: 0 0 auto;
    margin: 0 0 10px;
    padding-left: 8px;
    font-family: var(--font-num);
    font-size: 11.5px;
    letter-spacing: 0.14em;
    color: #9a9a9a;
}

.bt-rail-nav {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2px;
    overflow-y: auto;
    padding-right: 4px;
    scrollbar-width: thin;
}

.bt-rail-link {
    display: flex;
    align-items: baseline;
    gap: 8px;
    padding: 7px 8px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    line-height: 1.7;
    color: #6b6b6b;
    transition: background 0.18s ease, color 0.18s ease;
}

.bt-rail-link b {
    flex: 0 0 2em;
    text-align: right;
    font-family: var(--font-num);
    font-size: 11.5px;
    font-weight: 400;
    color: #b0b0b0;
}

/* 只占一行，超出省略；完整标题放在 title 里 */
.bt-rail-link span {
    flex: 1;
    min-width: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.bt-rail-link:hover {
    background: rgba(0, 0, 0, 0.04);
    color: #000;
}

/* 作者样式的 display:flex 会盖过 UA 的 [hidden]{display:none} */
.bt-rail-link[hidden] {
    display: none;
}

.bt-rail-link.is-active {
    background: #000;
    color: #fff;
}

.bt-rail-link.is-active b {
    color: rgba(255, 255, 255, 0.55);
}

/* 节首导览：一段一段的主题分组，替掉原来散落的加粗行 */
.bt-guide {
    margin: 0 0 28px;
    padding: 18px 22px 16px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: var(--radius-md);
    font-size: 14px;
    line-height: 1.95;
    color: #5a5a5a;
}

.bt-guide p {
    margin: 0 0 8px;
}

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

.bt-guide-title {
    font-family: var(--font-num);
    font-size: 11.5px;
    letter-spacing: 0.14em;
    color: #9a9a9a;
    margin: 0 0 10px;
}

.bt-guide strong {
    color: #000;
    font-weight: 600;
}

/* ===== 证据等级筛选：吸在页头下面 ===== */
.bt-tools {
    position: sticky;
    top: 56px;
    z-index: 18;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 10px 16px;
    margin-top: 26px;
    padding: 12px 0;
    background: rgba(250, 250, 250, 0.94);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

/* 长文没有条目，筛选条不出现；作者样式的 display:flex 会盖过 [hidden] */
.bt-tools[hidden] {
    display: none;
}

.bt-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.bt-chip {
    font-family: var(--font-num);
    font-size: 12px;
    line-height: 1;
    padding: 7px 12px;
    border: 1px solid rgba(0, 0, 0, 0.14);
    border-radius: 999px;
    background: #fff;
    color: #6b6b6b;
    cursor: pointer;
    transition: border-color 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.bt-chip b {
    font-weight: 400;
    color: #b0b0b0;
    margin-left: 3px;
}

.bt-chip:hover {
    border-color: #000;
    color: #000;
}

.bt-chip.is-active {
    background: #000;
    border-color: #000;
    color: #fff;
}

.bt-chip.is-active b {
    color: rgba(255, 255, 255, 0.6);
}

.bt-tools-note {
    font-size: 12px;
    color: #9a9a9a;
}

.bt-tools-count {
    margin-left: auto;
    font-family: var(--font-num);
    font-size: 12px;
    color: #9a9a9a;
    white-space: nowrap;
}

/* ===== 建议卡片 ===== */
.bt-items {
    margin-top: 24px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.bt-item {
    padding: 24px 26px 20px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: var(--radius-md);
    scroll-margin-top: 132px;
}

.bt-item[hidden] {
    display: none;
}

.bt-item:target {
    border-color: #000;
    box-shadow: 0 0 0 1px #000;
}

.bt-item-head {
    display: flex;
    align-items: baseline;
    gap: 10px;
    margin-bottom: 14px;
}

.bt-item-no {
    flex: 0 0 1.7em;
    font-family: var(--font-num);
    font-size: 12.5px;
    letter-spacing: 0.02em;
    color: #9a9a9a;
    text-align: right;
}

.bt-item-title {
    font-family: var(--font-display);
    font-size: 19.5px;
    font-weight: 600;
    line-height: 1.5;
    letter-spacing: 0.02em;
    color: #000;
    margin: 0;
    flex: 1;
    min-width: 0;
    overflow-wrap: anywhere;
}

/* 证据等级 */
.bt-ev {
    flex: 0 0 auto;
    width: 24px;
    height: 24px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    font-family: var(--font-num);
    font-size: 11.5px;
    line-height: 1;
    border: 1px solid #000;
    color: #000;
}

.bt-ev.ev-A {
    background: #000;
    color: #fff;
}

.bt-ev.ev-B {
    background: #fff;
    color: #000;
}

.bt-ev.ev-C {
    border-color: rgba(0, 0, 0, 0.22);
    color: #8a8a8a;
}

/* 说人话：左侧竖排标签栏 + 右侧正文，整块灰底 */
.bt-plain {
    display: grid;
    grid-template-columns: 40px minmax(0, 1fr);
    margin: 0 0 18px;
    background: #f4f4f2;
    border-radius: var(--radius-sm);
    overflow: hidden;
}

.bt-plain-tag {
    display: flex;
    justify-content: center;
    padding: 14px 12px 14px 0;
    background: rgba(0, 0, 0, 0.05);
    writing-mode: vertical-rl;
    text-orientation: upright;
    font-family: var(--font-sans);
    font-size: 12.5px;
    font-weight: 600;
    line-height: 1.6;
    letter-spacing: 8px; /* 竖排三个字之间上下各留 8px */
    color: #333;
}

.bt-plain-text {
    display: block;
    padding: 14px 18px;
    font-size: 16.5px;
    line-height: 1.9;
    color: #1a1a1a;
    overflow-wrap: anywhere;
}

.bt-fields {
    margin: 0;
}

.bt-row {
    display: grid;
    grid-template-columns: 52px minmax(0, 1fr);
    gap: 14px;
    padding: 10px 0;
    border-top: 1px solid rgba(0, 0, 0, 0.06);
}

.bt-row:first-child {
    border-top: none;
}

.bt-row dt {
    font-size: 12.5px;
    line-height: 2;
    color: #9a9a9a;
    letter-spacing: 0.06em;
}

.bt-row dd {
    margin: 0;
    font-size: 15.5px;
    line-height: 1.9;
    color: #2e2e2e;
    overflow-wrap: anywhere;
}

/* 备注比成本、收益再淡一档，扫读时不会抢走注意力 */
.bt-row-note dd {
    color: #5f5f5f;
    font-size: 15px;
}

/* ===== 来源：默认收起，一条一行 ===== */
.bt-src {
    margin-top: 16px;
    padding-top: 12px;
    border-top: 1px dashed rgba(0, 0, 0, 0.14);
}

.bt-src-head {
    display: flex;
    align-items: center;
    gap: 6px;
    margin: 0;
    font-family: var(--font-num);
    font-size: 11.5px;
    letter-spacing: 0.14em;
    color: #9a9a9a;
    cursor: pointer;
    list-style: none;
    transition: color 0.18s ease;
}

.bt-src-head::-webkit-details-marker {
    display: none;
}

.bt-src-head::after {
    content: '展开';
    margin-left: auto;
    letter-spacing: 0.04em;
}

.bt-src[open] .bt-src-head::after {
    content: '收起';
}

.bt-src-head:hover {
    color: #000;
}

.bt-src-head b {
    font-weight: 400;
    color: #000;
}

.bt-src-list {
    margin: 10px 0 0;
    padding: 0;
    list-style: none;
}

.bt-src-item {
    display: grid;
    grid-template-columns: 26px minmax(0, 1fr);
    gap: 10px;
    padding: 8px 0;
    border-top: 1px solid rgba(0, 0, 0, 0.05);
}

.bt-src-item:first-child {
    border-top: none;
    padding-top: 2px;
}

.bt-src-index {
    font-family: var(--font-num);
    font-size: 11px;
    line-height: 1.9;
    color: #c0c0c0;
}

.bt-src-text {
    margin: 0;
    font-size: 12.8px;
    line-height: 1.85;
    color: #7a7a7a;
    overflow-wrap: anywhere;
}

.bt-src-text a {
    color: #5a5a5a;
    border-bottom: 1px solid rgba(0, 0, 0, 0.14);
}

.bt-src-text a:hover {
    color: #000;
    border-color: #000;
}

.bt-src-text .bt-src-host {
    font-family: var(--font-num);
    font-size: 11.5px;
    color: #000;
    white-space: nowrap;
    border-bottom-color: rgba(0, 0, 0, 0.3);
}

/* 长文正文 */
.bt-md-h {
    font-family: var(--font-display);
    font-weight: 700;
    color: #000;
    letter-spacing: 0.02em;
}

.bt-md-h2 {
    font-size: 23px;
    line-height: 1.5;
    margin: 40px 0 16px;
    padding-bottom: 10px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.bt-md-h3 {
    font-size: 18px;
    line-height: 1.6;
    margin: 28px 0 10px;
}

.bt-md-list {
    margin: 0 0 18px;
    padding-left: 1.4em;
    font-size: 16px;
    line-height: 1.9;
}

.bt-md-list li {
    list-style: disc;
    margin-bottom: 6px;
}

.bt-md-list li::marker {
    color: #b0b0b0;
}

/* 有序列表：保留原文编号 */
ol.bt-md-list {
    list-style: decimal;
}

ol.bt-md-list li {
    list-style: decimal;
}

.bt-hr {
    border: 0;
    border-top: 1px solid rgba(0, 0, 0, 0.08);
    margin: 32px 0;
}

.bt-table-wrap {
    overflow-x: auto;
    margin: 0 0 22px;
}

.bt-table-wrap table {
    border-collapse: collapse;
    width: 100%;
    font-size: 14px;
}

.bt-table-wrap th,
.bt-table-wrap td {
    border: 1px solid rgba(0, 0, 0, 0.1);
    padding: 9px 12px;
    text-align: left;
    vertical-align: top;
    line-height: 1.7;
}

.bt-table-wrap th {
    background: #f4f4f4;
    font-weight: 600;
    white-space: nowrap;
}

/* 状态与导航 */
.bt-status {
    font-size: 15px;
    line-height: 1.9;
    color: #6b6b6b;
    margin: 0;
}

.bt-status a {
    color: #000;
    border-bottom: 1px solid rgba(0, 0, 0, 0.2);
}

.bt-status-error {
    color: #4a4a4a;
}

.bt-status-detail {
    display: inline-block;
    margin-top: 6px;
    font-size: 13.5px;
    line-height: 1.8;
    color: #8a8a8a;
}

.bt-issue-nav {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 32px;
    max-width: 820px;
    margin-top: 56px;
    padding-top: 28px;
    border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.bt-issue-back {
    font-size: 14px;
    color: #6b6b6b;
}

.bt-issue-back:hover {
    color: #000;
}

.bt-issue-next {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 6px;
    max-width: 64%;
    text-align: right;
}

.bt-issue-nav-label {
    font-size: 12px;
    letter-spacing: 0.1em;
    color: #9a9a9a;
}

.bt-issue-nav-title {
    font-family: var(--font-display);
    font-size: 18px;
    font-weight: 600;
    line-height: 1.5;
    color: #000;
}

/* ===== 响应式 ===== */
@media (max-width: 1160px) {
    /* 放不下右侧目录时收起，正文回到单列 */
    .bt-doc-layout {
        grid-template-columns: minmax(0, 1fr);
    }

    .bt-rail {
        display: none;
    }
}

@media (max-width: 968px) {
    .bt-hero {
        padding: 24px 0 40px;
    }

    /* 左目录变成一行可换行的胶囊 */
    .bt-layout {
        grid-template-columns: 1fr;
        gap: 28px;
    }

    .bt-side {
        position: static;
    }

    /* 目录页：桌面侧栏收起，改用折叠目录 */
    .bt-layout-book {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .bt-side-book {
        display: none;
    }

    .bt-toc {
        display: block;
    }

    .bt-nav-title,
    .bt-side-tip {
        display: none;
    }

    .bt-nav {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 8px;
    }

    .bt-nav-link {
        gap: 8px;
        padding: 8px 14px;
        background: #fff;
        border: 1px solid rgba(0, 0, 0, 0.12);
        border-radius: 999px;
        font-size: 13.5px;
    }

    .bt-nav-link:hover {
        background: #fff;
        border-color: #000;
    }

    .bt-nav-link.is-active {
        border-color: #000;
    }

    .bt-section {
        margin-top: 48px;
    }
}

@media (max-width: 860px) {
    .bt-hub-feature {
        grid-template-columns: 1fr;
        gap: 22px;
    }

    .bt-hub-cta {
        justify-self: start;
    }

    .bt-toolbar {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }

    .bt-toolbar .bt-count {
        order: 2;
    }
}

@media (max-width: 600px) {
    .bt-res,
    .bt-item {
        padding: 20px 18px;
    }

    .bt-tools {
        top: 56px;
        gap: 8px;
        margin-top: 18px;
        padding: 10px 0;
    }

    .bt-tools-note {
        display: none;
    }

    .bt-item-no {
        flex-basis: 1.4em;
        font-size: 12px;
    }

    .bt-src-item {
        grid-template-columns: 22px minmax(0, 1fr);
        gap: 8px;
    }

    .bt-book-row {
        grid-template-columns: 30px minmax(0, 1fr);
        gap: 12px;
        padding: 16px 18px;
    }

    .bt-book-title {
        font-size: 17px;
    }

    .bt-book-meta {
        grid-column: 2;
        margin-top: 4px;
        text-align: left;
        white-space: normal;
    }

    .bt-book-meta b {
        font-size: 18px;
    }

    .bt-book-ev {
        display: inline;
        margin-left: 10px;
    }

    .bt-section {
        margin-top: 48px;
    }

    .bt-issue {
        padding: 48px 0;
    }

    .bt-body {
        font-size: 15.5px;
    }

    .bt-plain {
        grid-template-columns: 36px minmax(0, 1fr);
    }

    .bt-plain-tag {
        padding: 12px 10px 12px 0;
        font-size: 12px;
    }

    .bt-plain-text {
        padding: 13px 16px;
        font-size: 15.5px;
    }

    .bt-item-title {
        font-size: 18px;
    }

    .bt-row {
        grid-template-columns: 1fr;
        gap: 2px;
    }

    .bt-row dt {
        font-size: 12px;
    }

    .bt-issue-nav {
        flex-direction: column;
        align-items: flex-start;
        gap: 22px;
    }

    .bt-issue-next {
        align-items: flex-start;
        max-width: 100%;
        text-align: left;
    }
}