.site-nav{display:inline-flex;align-items:center;white-space:nowrap;background:var(--deep);color:#fff;text-decoration:none;border-radius:8px;padding:10px 15px;font-weight:700;font-size:14px}
.site-nav:hover{filter:brightness(1.08)}
.cards-header{display:flex;justify-content:space-between;align-items:flex-start;gap:20px;margin-bottom:20px}
.card-tabs{display:inline-flex;background:#fff;border:1px solid var(--line);border-radius:8px;padding:4px;gap:4px;margin-bottom:16px}
.card-tabs button{background:#fff;border:0;border-radius:7px;color:var(--ink);padding:9px 15px;font-weight:700}
.card-tabs button.active{background:var(--deep);color:#fff}
.cards-toolbar{margin-bottom:8px}
.toolbar-row{display:grid;grid-template-columns:1.6fr repeat(5,minmax(0,1fr));gap:12px}
.tab-book .toolbar-row{grid-template-columns:2fr 1fr 2fr}
.toolbar-meta{display:flex;justify-content:space-between;align-items:center;gap:14px;margin-top:14px}
.view-switch{display:flex;border:1px solid var(--line);border-radius:8px;overflow:hidden}
.view-switch button{background:#fff;color:var(--ink);border:0;border-radius:0;padding:8px 14px;font-weight:700}
.view-switch button.active{background:var(--deep);color:#fff}
.card-groups{margin-top:18px}
.lesson-group{margin-bottom:24px}
.lesson-head{display:flex;justify-content:space-between;align-items:baseline;gap:14px;border-bottom:1px solid var(--line);padding-bottom:8px;margin-bottom:14px}
.lesson-head h2{margin:0}
.lesson-head .hint{margin:0}
.card-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(340px,1fr));gap:16px;align-items:stretch}
.knowledge-card{background:#fff;border:1px solid var(--line);border-top:3px solid var(--blue);border-radius:8px;padding:16px;display:grid;gap:10px;align-content:start}
.knowledge-card.level-初级{border-top-color:#2f7d4f}
.knowledge-card.level-中级{border-top-color:#1a6e8a}
.knowledge-card.level-高级{border-top-color:#a35b12}
.card-head{display:flex;justify-content:space-between;align-items:flex-start;gap:10px}
.card-head h3{font-size:15px;line-height:1.45;margin:0}
.card-tags{display:flex;flex-wrap:wrap;justify-content:flex-end;gap:6px;flex:0 0 auto}
.card-meta{font-size:12px;color:var(--muted);margin:0}
.card-core{margin:0;line-height:1.65}
.card-action{margin:0;background:#f7fafc;border:1px solid var(--line);border-radius:8px;padding:10px 11px;font-size:13px;line-height:1.55}
.card-more{border-top:1px solid var(--line);padding-top:8px}
.card-more summary{cursor:pointer;font-size:13px;font-weight:700;color:var(--deep)}
.card-more ul{margin:8px 0 0;padding-left:20px;font-size:13px;line-height:1.6}
.skill-tags{display:flex;flex-wrap:wrap;gap:6px}
.chip{display:inline-block;border-radius:999px;padding:2px 9px;font-size:11px;font-weight:700;border:1px solid var(--line);background:#eef2f8;color:#3d4b63}
.chip.review-review{background:#e9f7ef;border-color:#bfe5cd;color:#1d6f42}
.chip.review-needs_review{background:#fff4e5;border-color:#f0c36d;color:#9a3412}
.chip.skill{background:var(--safe);border-color:var(--margin);color:var(--deep)}
.empty-state{text-align:center;color:var(--muted);padding:36px 20px;display:grid;gap:14px;justify-items:center}
@media(max-width:900px){.cards-header{display:block}.cards-header .site-nav{display:inline-flex;margin-top:14px}.toolbar-row{grid-template-columns:1fr}.toolbar-meta{flex-direction:column;align-items:stretch}.view-switch{width:100%}.view-switch button{flex:1}.card-grid{grid-template-columns:1fr}.lesson-head{flex-direction:column;align-items:flex-start}}

/* Textbook reader: chapter order is the navigation, source details are secondary. */
.library-note{color:var(--muted);font-size:13px;margin:14px 0 24px}
.book-mode-switch{width:fit-content;margin:0 0 20px}
.semantic-points h4{margin:0 0 6px;font-size:15px}
.semantic-points ul{margin:0;padding-left:20px;font-size:15px;line-height:1.9}
.card-application{font-size:14px;line-height:1.8;margin:0}
.semantic-boundary{background:#f6f8fb;padding:12px;border:1px solid var(--line);border-radius:6px}
.semantic-boundary ul{font-size:14px}
.semantic-card .card-more ol{font-size:14px;line-height:1.8;padding-left:22px}
.semantic-card .hint{font-size:12px}
.knowledge-reader{padding:28px 40px;max-width:840px;margin:auto}
.claim-evidence{border-bottom:1px solid var(--line);padding:16px 0}
.claim-evidence blockquote{margin:12px 0;padding-left:16px;border-left:3px solid #a7bfcb;font-size:15px;line-height:1.9}
.tab-book .card-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
.book-card{padding:24px;gap:14px;position:relative}
.book-card h3{margin:0;font-size:21px;line-height:1.5;font-family:"Microsoft YaHei UI","Microsoft YaHei",sans-serif}
.chapter-number{display:flex;justify-content:space-between;margin:0;color:var(--muted);font-size:12px;letter-spacing:.06em}
.chapter-number span{letter-spacing:0}
.chapter-purpose{margin:0;font-size:15px;line-height:1.7;color:var(--deep)}
.chapter-points{display:grid;gap:12px;border-top:1px solid var(--line);padding-top:16px}
.chapter-points h4{font-size:14px;margin:0 0 5px;color:var(--ink)}
.chapter-points p{font-size:14px;line-height:1.8;margin:0;color:#4b5c70;display:-webkit-box;-webkit-box-orient:vertical;-webkit-line-clamp:3;overflow:hidden}
.read-chapter{margin-top:4px;text-align:left;display:flex;justify-content:space-between;align-items:center;border:0;border-top:1px solid var(--line);border-radius:0;background:transparent;color:var(--deep);padding:14px 0 0;font-size:14px;font-weight:700}
.read-chapter:hover{color:#1a6e8a;background:transparent}
.book-card:has(.read-chapter:focus-visible){outline:3px solid #89adc4;outline-offset:3px}
body.reading-book{overflow:hidden}
#book-reader{width:min(1080px,calc(100vw - 48px));max-width:1080px;max-height:calc(100dvh - 48px);padding:0;border:1px solid var(--line);border-radius:12px;color:var(--ink);background:#fff;overflow:auto}
#book-reader::backdrop{background:rgba(16,37,59,.52)}
.reader-header{position:sticky;top:0;z-index:2;display:flex;align-items:flex-start;justify-content:space-between;gap:20px;padding:20px 28px;background:#fff;border-bottom:1px solid var(--line)}
.reader-header h2{font-size:24px;margin:0;line-height:1.5}
#reader-kicker{margin:0 0 5px;color:var(--muted);font-size:12px}
#reader-close{flex-shrink:0;background:#eef2f8;color:var(--deep);border:1px solid var(--line);padding:8px 12px}
.reader-layout{display:grid;grid-template-columns:235px minmax(0,1fr);gap:32px;padding:28px}
.reader-index{align-self:start;position:sticky;top:118px;max-height:calc(100dvh - 210px);overflow:auto;padding-right:12px;border-right:1px solid var(--line);display:flex;flex-direction:column;gap:8px}
.reader-index a{font-size:13px;line-height:1.6;color:#40556c;text-decoration:none;padding:4px 6px;border-radius:4px}
.reader-index a:hover,.reader-index a:focus-visible{background:#edf4f7;color:#10253b}
.reader-index .index-level-2{padding-left:18px;font-size:12px}
.reader-body{min-width:0}
.reader-body h3{font-size:19px;line-height:1.6;margin:0 0 12px}
.reader-body h4{font-size:15px;margin:18px 0 8px}
.reader-body p,.reader-body li{font-size:16px;line-height:1.95;overflow-wrap:anywhere}
.reader-guide{background:#f4f8fa;padding:20px;border-left:3px solid #1a6e8a;margin-bottom:30px}
.reader-guide p{margin:6px 0}
.reader-body .hint,.section-parent{font-size:12px!important;color:var(--muted)}
.reader-section{margin-bottom:30px;scroll-margin-top:125px}
.reader-section p{margin:10px 0}
.reader-level-1{border-top:1px solid var(--line);padding-top:24px}
.reader-level-2 h3{font-size:17px}
.reader-exercise{background:#f2f8f4;padding:22px;margin:28px 0;scroll-margin-top:125px}
.reader-exercise p{margin:8px 0}
.reader-exercise ul{padding-left:22px}
.source-detail{font-size:12px;color:var(--muted);padding:12px 0;scroll-margin-top:125px}
.source-detail summary{cursor:pointer;font-size:12px}
.source-detail p,.source-detail li{font-size:12px;line-height:1.7}
.source-hash{word-break:break-all}
.restricted-note{border-left:3px solid #a35b12;padding:15px;background:#fff8ef}
button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid #6c9fbd;outline-offset:3px}
@media(max-width:900px){.tab-book .toolbar-row,.tab-book .card-grid{grid-template-columns:1fr}.book-card{padding:18px}#book-reader{width:calc(100vw - 20px);max-height:calc(100dvh - 20px)}.reader-layout{grid-template-columns:1fr;padding:18px;gap:18px}.reader-index{position:static;max-height:160px;border:1px solid var(--line);padding:10px}.reader-header{padding:14px 18px}.reader-header h2{font-size:19px}.reader-body p,.reader-body li{font-size:15px}.reader-guide,.reader-exercise{padding:16px}}