:root {
  --catalog-bg: #f5faf7;
  --catalog-green: #08794d;
  --catalog-green-dark: #075d3e;
  --catalog-text: #10251b;
  --catalog-muted: #66766d;
  --catalog-line: #d7e4dc;
  --catalog-blue: #1388ce;
  --catalog-orange: #ef7a22;
}

body { background: var(--catalog-bg); color: var(--catalog-text); }
.catalog-shell, .textbook-shell { width: min(1160px, calc(100% - 40px)); margin: 0 auto; padding: 52px 0 64px; }
.catalog-heading { margin-bottom: 26px; }
.catalog-eyebrow { margin: 0 0 8px; color: var(--catalog-green); font-size: 14px; font-weight: 700; }
.catalog-heading h1, .textbook-intro h1 { margin: 0; color: var(--catalog-text); font-size: clamp(34px, 4vw, 50px); line-height: 1.12; letter-spacing: -0.03em; }
.catalog-heading > p:last-child { margin: 12px 0 0; color: var(--catalog-muted); font-size: 17px; line-height: 1.7; }

.catalog-filters { display: grid; grid-template-columns: 250px 205px minmax(500px, 1fr) 190px; gap: 0; margin-bottom: 24px; overflow: hidden; border: 1px solid var(--catalog-line); border-radius: 8px; background: #fff; }
.filter-group { min-width: 0; padding: 18px; border-right: 1px solid var(--catalog-line); }
.filter-group:last-child { border-right: 0; }
.filter-label { display: block; margin-bottom: 11px; color: var(--catalog-text); font-size: 14px; font-weight: 700; }
.filter-options { display: flex; min-width: 0; gap: 6px; }
.filter-button, .edition-select { min-height: 42px; border: 1px solid var(--catalog-line); border-radius: 6px; background: #fff; color: #34473d; font: inherit; font-size: 14px; cursor: pointer; }
.filter-button { padding: 0 13px; white-space: nowrap; }
.filter-button:hover, .filter-button:focus-visible, .edition-select:focus-visible { border-color: var(--catalog-green); outline: 2px solid rgba(8,121,77,.13); outline-offset: 1px; }
.filter-button.is-active { border-color: var(--catalog-green); background: var(--catalog-green); color: #fff; font-weight: 700; }
.edition-select { width: 100%; padding: 0 34px 0 12px; }
.grade-options { overflow-x: auto; padding-bottom: 2px; scrollbar-width: thin; }
.mobile-filter-summary { display: none; }

.catalog-results { min-height: 300px; }
.result-summary { display: flex; align-items: baseline; justify-content: space-between; gap: 18px; margin-bottom: 18px; }
.result-summary strong { font-size: 16px; }
.result-summary span { color: var(--catalog-muted); font-size: 14px; text-align: right; }
.catalog-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 18px; }
.catalog-card { min-width: 0; overflow: hidden; border: 1px solid var(--catalog-line); border-radius: 8px; background: #fff; transition: border-color .18s ease, transform .18s ease; }
.catalog-card:hover { border-color: var(--catalog-green); transform: translateY(-2px); }
.catalog-card a { display: flex; height: 100%; flex-direction: column; color: inherit; text-decoration: none; }
.catalog-cover { display: grid; min-height: 284px; place-items: center; padding: 16px 16px 8px; background: #fbfdfc; }
.catalog-cover img { display: block; width: auto; max-width: 100%; height: 268px; object-fit: contain; }
.catalog-card-copy { display: block; padding: 14px 16px 17px; }
.subject-tag { display: inline-flex; min-height: 25px; align-items: center; margin-bottom: 9px; padding: 0 8px; border-radius: 4px; background: #e9f6ef; color: var(--catalog-green); font-size: 12px; font-weight: 700; }
.catalog-card[data-subject="数学"] .subject-tag { background: #e9f5fb; color: var(--catalog-blue); }
.catalog-card[data-subject="英语"] .subject-tag { background: #fff1e7; color: var(--catalog-orange); }
.catalog-card-copy strong { display: block; min-height: 48px; font-size: 16px; line-height: 1.5; }
.catalog-card-copy em { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-top: 9px; color: var(--catalog-muted); font-size: 13px; font-style: normal; }
.catalog-card-copy i { width: 1px; height: 12px; background: var(--catalog-line); }
.catalog-empty { padding: 70px 20px; border: 1px dashed var(--catalog-line); border-radius: 8px; background: #fff; text-align: center; }
.catalog-empty strong, .catalog-empty span { display: block; }
.catalog-empty span { margin-top: 8px; color: var(--catalog-muted); }
.load-more { display: block; min-width: 220px; min-height: 46px; margin: 28px auto 0; padding: 0 22px; border: 1px solid var(--catalog-green); border-radius: 6px; background: #fff; color: var(--catalog-green); font: inherit; font-weight: 700; cursor: pointer; }
.load-more[hidden] { display: none; }
.load-more:hover { background: #edf8f2; }
.catalog-wechat { margin-top: 54px; }

@media (min-width: 1181px) {
  .filter-subject .filter-options { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 5px; }
  .filter-subject .filter-button { min-width: 0; padding-inline: 7px; }
  .filter-grade .filter-options { gap: 4px; }
  .filter-grade .filter-button { padding-inline: 10px; }
  .filter-semester .filter-options { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 5px; }
  .filter-semester .filter-button { min-width: 0; padding-inline: 6px; }
}

.breadcrumb { display: flex; flex-wrap: wrap; gap: 9px; margin-bottom: 24px; color: var(--catalog-muted); font-size: 14px; }
.breadcrumb a { color: var(--catalog-green); }
.textbook-hero { display: grid; grid-template-columns: minmax(260px, 360px) minmax(0, 1fr); gap: clamp(34px, 6vw, 76px); align-items: center; padding: clamp(28px, 5vw, 58px); border: 1px solid var(--catalog-line); border-radius: 8px; background: #fff; }
.textbook-cover-large { display: grid; place-items: center; min-height: 430px; }
.textbook-cover-large img { display: block; width: auto; max-width: 100%; max-height: 430px; object-fit: contain; box-shadow: 0 16px 36px rgba(16,38,29,.12); }
.textbook-intro > p:not(.catalog-eyebrow) { max-width: 620px; margin: 18px 0 0; color: var(--catalog-muted); font-size: 16px; line-height: 1.8; }
.textbook-intro dl { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 0; margin: 28px 0; border-top: 1px solid var(--catalog-line); border-bottom: 1px solid var(--catalog-line); }
.textbook-intro dl div { display: grid; grid-template-columns: 88px 1fr; gap: 8px; padding: 13px 0; border-bottom: 1px solid var(--catalog-line); }
.textbook-intro dl div:nth-last-child(-n+2) { border-bottom: 0; }
.textbook-intro dt { color: var(--catalog-muted); }
.textbook-intro dd { margin: 0; font-weight: 700; }
.hero-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.primary-link, .secondary-link { display: inline-flex; min-height: 46px; align-items: center; justify-content: center; padding: 0 20px; border-radius: 6px; text-decoration: none; font-weight: 700; }
.secondary-link { border: 1px solid var(--catalog-green); color: var(--catalog-green); }
.text-link { padding: 10px 4px; color: var(--catalog-muted); }
.textbook-preview-section { margin-top: 28px; padding: clamp(24px, 4vw, 44px); border: 1px solid var(--catalog-line); border-radius: 8px; background: #fff; }
.textbook-preview-grid { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 20px; }
.textbook-preview-grid figure { min-width: 0; margin: 0; overflow: hidden; border: 1px solid var(--catalog-line); border-radius: 7px; }
.textbook-preview-grid img { display: block; width: 100%; height: auto; background: #f3f7f5; }
.textbook-preview-grid figcaption { padding: 12px 14px; color: var(--catalog-muted); font-size: 14px; }
.pdf-preview-section { margin-top: 38px; padding-top: 32px; border-top: 1px solid var(--catalog-line); }
.pdf-preview-section .section-head { margin-bottom: 18px; }
.pdf-preview-grid { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 18px; }
.pdf-preview-card { display: block; min-width: 0; padding: 8px; overflow: hidden; border: 1px solid var(--catalog-line); border-radius: 7px; background: #f8fbf9; cursor: zoom-in; transition: border-color .18s ease, box-shadow .18s ease, transform .18s ease; }
.pdf-preview-card:hover { border-color: #9ecdb3; box-shadow: 0 10px 24px rgba(16,38,29,.08); transform: translateY(-2px); }
.pdf-preview-card:focus-visible { outline: 3px solid rgba(7,151,102,.2); outline-offset: 3px; }
.pdf-preview-card img { display: block; width: 100%; aspect-ratio: 210 / 297; object-fit: contain; background: #fff; }
.pdf-lightbox[hidden] { display: none; }
.pdf-lightbox { position: fixed; inset: 0; z-index: 1200; display: grid; place-items: center; padding: 28px; }
.pdf-lightbox-backdrop { position: absolute; inset: 0; background: rgba(12,28,21,.76); }
.pdf-lightbox-dialog { position: relative; z-index: 1; display: grid; place-items: center; width: min(760px,100%); max-height: calc(100dvh - 56px); }
.pdf-lightbox-dialog img { display: block; width: auto; max-width: 100%; max-height: calc(100dvh - 56px); object-fit: contain; background: #fff; box-shadow: 0 24px 70px rgba(0,0,0,.28); }
.pdf-lightbox-close { position: absolute; top: 10px; right: 10px; z-index: 2; display: grid; width: 42px; height: 42px; place-items: center; border: 1px solid var(--catalog-line); border-radius: 50%; background: rgba(255,255,255,.96); color: var(--catalog-text); font-size: 26px; line-height: 1; cursor: pointer; }
.textbook-not-found { padding: 80px 24px; border: 1px solid var(--catalog-line); border-radius: 8px; background: #fff; text-align: center; }
.textbook-not-found p { margin: 12px 0 24px; color: var(--catalog-muted); }
.textbook-not-found .primary-link { background: var(--catalog-green); color: #fff; }

@media (max-width: 1180px) {
  .catalog-filters { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .filter-group:nth-child(2) { border-right: 0; }
  .filter-group:nth-child(-n+2) { border-bottom: 1px solid var(--catalog-line); }
  .catalog-grid { grid-template-columns: repeat(3,minmax(0,1fr)); }
}

@media (max-width: 680px) {
  .catalog-shell, .textbook-shell { width: min(100% - 28px, 1160px); padding: 28px 0 44px; }
  .site-header { min-height: 64px; }
  .site-nav { max-width: 100%; justify-content: flex-start; overflow-x: auto; white-space: nowrap; scrollbar-width: none; }
  .site-nav::-webkit-scrollbar { display: none; }
  .catalog-heading { margin-bottom: 20px; }
  .catalog-heading h1, .textbook-intro h1 { font-size: 31px; }
  .catalog-heading > p:last-child { font-size: 15px; }
  .catalog-filters { display: block; border-radius: 8px; }
  .mobile-filter-summary { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 14px; border-bottom: 1px solid var(--catalog-line); }
  .mobile-filter-summary strong { overflow: hidden; font-size: 14px; text-overflow: ellipsis; white-space: nowrap; }
  .mobile-filter-summary button { min-width: 76px; min-height: 44px; padding: 0 14px; border: 0; border-radius: 6px; background: var(--catalog-green); color: #fff; font: inherit; font-weight: 700; }
  .filter-edition { display: none; }
  .filter-edition.is-mobile-open { display: block; }
  .filter-group { padding: 14px; border-right: 0; border-bottom: 1px solid var(--catalog-line); }
  .filter-group:last-child { border-bottom: 0; }
  .filter-label { margin-bottom: 9px; }
  .filter-options { overflow-x: auto; padding-bottom: 2px; }
  .filter-options { scrollbar-width: none; }
  .filter-options::-webkit-scrollbar { display: none; }
  .filter-button { min-height: 44px; padding-inline: 16px; }
  .edition-select { min-height: 46px; }
  .result-summary { display: block; }
  .result-summary span { display: block; margin-top: 6px; text-align: left; }
  .catalog-grid { grid-template-columns: repeat(2,minmax(0,1fr)); gap: 12px; }
  .catalog-cover { min-height: 190px; padding: 10px 8px 5px; }
  .catalog-cover img { height: 185px; }
  .catalog-card-copy { padding: 11px 11px 14px; }
  .catalog-card-copy strong { min-height: 64px; font-size: 14px; line-height: 1.55; }
  .catalog-card-copy em { display: block; margin-top: 7px; line-height: 1.55; }
  .catalog-card-copy i { display: none; }
  .catalog-wechat { margin-top: 38px; }
  .textbook-hero { grid-template-columns: 1fr; gap: 24px; padding: 22px 18px; }
  .textbook-cover-large { min-height: 0; }
  .textbook-cover-large img { max-height: 390px; }
  .textbook-intro dl { grid-template-columns: 1fr; }
  .textbook-intro dl div:nth-last-child(2) { border-bottom: 1px solid var(--catalog-line); }
  .hero-actions { align-items: stretch; flex-direction: column; }
  .hero-actions .download-button, .hero-actions .secondary-link { width: 100%; }
  .text-link { text-align: center; }
  .textbook-preview-section { padding: 22px 16px; }
  .textbook-preview-grid { grid-template-columns: 1fr; }
  .pdf-preview-section { margin-top: 28px; padding-top: 24px; }
  .pdf-preview-grid { grid-template-columns: 1fr; gap: 20px; }
  .pdf-preview-card { padding: 0; background: #fff; }
  .pdf-preview-card img { height: auto; aspect-ratio: auto; }
  .pdf-lightbox { padding: 14px; }
  .pdf-lightbox-dialog { max-height: calc(100dvh - 28px); }
  .pdf-lightbox-dialog img { max-height: calc(100dvh - 28px); }
  .download-modal { align-items: end; }
}

@media (max-width: 390px) {
  .catalog-shell, .textbook-shell { width: calc(100% - 24px); }
  .catalog-cover img { height: 172px; }
  .catalog-card-copy strong { font-size: 13px; }
}

.catalog-directory-link { display: inline-block; margin-top: 14px; color: var(--catalog-green); font-weight: 700; text-underline-offset: 4px; }
.textbook-directory { width: min(1160px, calc(100% - 40px)); margin: 0 auto; padding: 34px 0 56px; }
.directory-heading { padding: 34px 0 28px; border-bottom: 1px solid var(--catalog-line); }
.directory-heading h1 { margin: 6px 0 10px; font-size: clamp(32px, 5vw, 52px); }
.directory-heading > p:not(.catalog-eyebrow) { color: var(--catalog-muted); }
.directory-heading .primary-link { display: inline-block; margin-top: 18px; }
.directory-subject { padding: 34px 0 8px; }
.directory-subject > h2 { margin: 0 0 20px; font-size: 28px; }
.directory-edition { margin: 0 0 24px; padding: 22px 24px; border: 1px solid var(--catalog-line); border-radius: 12px; background: #fff; }
.directory-edition h3 { margin: 0 0 14px; font-size: 19px; }
.directory-edition ul { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px 24px; margin: 0; padding: 0; list-style: none; }
.directory-edition a { color: var(--catalog-text); line-height: 1.55; text-underline-offset: 3px; }
.directory-edition a:hover { color: var(--catalog-green); }

@media (max-width: 760px) {
  .textbook-directory { width: calc(100% - 28px); padding-top: 12px; }
  .directory-heading { padding: 24px 0; }
  .directory-subject > h2 { font-size: 24px; }
  .directory-edition { padding: 18px; }
  .directory-edition ul { grid-template-columns: 1fr; gap: 9px; }
}

/* English textbook word lists - static HTML, no audio controls. */
.textbook-wordlist-section { margin-top: 38px; padding-top: 32px; border-top: 1px solid var(--catalog-line); }
.textbook-wordlist-section .section-head { align-items: end; margin-bottom: 18px; }
.textbook-wordlist-section .section-head h2 { margin: 0; font-size: clamp(26px,3vw,34px); }
.textbook-wordlist-section .section-head span { color: var(--catalog-muted); font-size: 14px; }
.textbook-wordlist-source-note { margin: -6px 0 20px; color: var(--catalog-muted); font-size: 14px; line-height: 1.7; }
.textbook-word-unit-nav { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 28px; }
.textbook-word-unit-nav a { display: inline-flex; min-height: 40px; align-items: center; padding: 0 14px; border: 1px solid var(--catalog-line); border-radius: 999px; background: #f7fbf9; color: var(--catalog-green); font-size: 14px; font-weight: 700; text-decoration: none; }
.textbook-word-unit-nav a:hover, .textbook-word-unit-nav a:focus-visible { border-color: var(--catalog-green); outline: 2px solid rgba(8,121,77,.13); outline-offset: 1px; }
.textbook-word-unit { scroll-margin-top: 86px; }
.textbook-word-unit + .textbook-word-unit { margin-top: 34px; }
.textbook-word-unit h3 { margin: 0 0 14px; color: var(--catalog-text); font-size: 21px; }
.textbook-word-unit-head { display: flex; align-items: center; justify-content: space-between; gap: 14px; margin-bottom: 14px; }
.textbook-word-unit-head h3 { margin: 0; }
.textbook-word-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 10px; }
.textbook-word-card { min-width: 0; padding: 16px 18px; border: 1px solid var(--catalog-line); border-radius: 7px; background: #fff; }
.textbook-word-audio { display: flex; align-items: flex-start; gap: 14px; min-width: 0; }
.textbook-word-copy { min-width: 0; flex: 1 1 auto; }
.textbook-word-audio .textbook-word-audio-button { margin-top: 1px; }
.textbook-word-english, .textbook-word-ipa, .textbook-word-chinese { display: block; overflow-wrap: anywhere; }
.textbook-word-english { color: #1769b0; font-size: 18px; line-height: 1.35; }
.textbook-word-ipa { margin-top: 5px; color: #4a5d53; font-family: "Segoe UI","Arial Unicode MS",sans-serif; font-size: 15px; line-height: 1.45; }
.textbook-word-chinese { margin-top: 5px; color: var(--catalog-text); font-size: 15px; line-height: 1.55; }

body.continuous-audio-open { overflow: hidden; }
.continuous-audio-modal[hidden] { display: none; }
.continuous-audio-modal { position: fixed; inset: 0; z-index: 10010; display: grid; place-items: center; padding: 24px; }
.continuous-audio-backdrop { position: absolute; inset: 0; background: rgba(8,35,25,.48); }
.continuous-audio-dialog { position: relative; z-index: 1; width: min(920px,100%); max-height: calc(100vh - 48px); overflow: auto; padding: 30px; border: 1px solid var(--catalog-line); border-radius: 10px; background: #f8fcf9; box-shadow: 0 28px 90px rgba(8,35,25,.24); }
.continuous-audio-head { display: flex; align-items: center; justify-content: space-between; gap: 18px; margin-bottom: 18px; }
.continuous-audio-head h2 { margin: 0; color: var(--catalog-text); font-size: 24px; line-height: 1.3; }
.continuous-audio-head-actions { display: flex; align-items: center; gap: 26px; color: var(--catalog-text); font-size: 16px; font-weight: 700; white-space: nowrap; }
.continuous-audio-head-actions button { min-height: 36px; padding: 0; border: 0; background: transparent; color: var(--catalog-green); font: inherit; font-weight: 700; cursor: pointer; }
.continuous-audio-head-actions button:hover, .continuous-audio-head-actions button:focus-visible { color: var(--catalog-green-dark); text-decoration: underline; text-underline-offset: 4px; }
.continuous-audio-card { position: relative; display: grid; min-height: 370px; place-items: center; padding: 54px 90px 74px; border: 1px solid #acd5c0; border-radius: 10px; background: #fff; }
.continuous-audio-copy { display: grid; justify-items: center; gap: 14px; max-width: 100%; text-align: center; }
.continuous-audio-copy strong { max-width: 100%; color: #075c3d; font-size: clamp(48px,7vw,82px); font-weight: 800; line-height: 1.08; overflow-wrap: anywhere; }
.continuous-audio-copy span { display: block; max-width: 100%; overflow-wrap: anywhere; }
.continuous-audio-copy [data-continuous-audio-ipa] { color: #164f3b; font-family: "Segoe UI","Arial Unicode MS",sans-serif; font-size: clamp(22px,3vw,34px); line-height: 1.35; }
.continuous-audio-copy [data-continuous-audio-chinese] { color: #164f3b; font-size: clamp(22px,3vw,34px); line-height: 1.4; }
.continuous-audio-toggle { position: absolute; right: 26px; bottom: 24px; display: inline-grid; width: 48px; height: 48px; place-items: center; padding: 0; border: 2px solid var(--catalog-green); border-radius: 50%; background: #fff; cursor: pointer; }
.continuous-audio-toggle:hover, .continuous-audio-toggle:focus-visible { background: #eef8f2; outline: 3px solid rgba(8,121,77,.14); outline-offset: 2px; }
.continuous-audio-toggle img { display: block; width: 24px; height: 24px; }

@media (max-width: 900px) {
  .textbook-word-grid { grid-template-columns: repeat(2,minmax(0,1fr)); }
}

@media (max-width: 760px) {
  .textbook-wordlist-section { margin-top: 28px; padding-top: 24px; }
  .textbook-wordlist-section .section-head { display: block; }
  .textbook-wordlist-section .section-head > span { display: block; margin-top: 6px; }
  .textbook-word-unit-nav { flex-wrap: nowrap; margin-right: -16px; padding-right: 16px; overflow-x: auto; scrollbar-width: thin; }
  .textbook-word-unit-nav a { flex: 0 0 auto; }
  .textbook-word-unit-head { align-items: center; }
  .textbook-word-grid { grid-template-columns: 1fr; }
  .textbook-word-card { padding: 15px 16px; }
  .textbook-word-audio { gap: 16px; }
  .textbook-word-audio .textbook-word-audio-button { min-width: 54px; min-height: 38px; padding: 6px 12px; font-size: 14px; }
  .continuous-audio-modal { padding: 14px; }
  .continuous-audio-dialog { width: min(100%,560px); max-height: calc(100vh - 28px); padding: 20px; border-radius: 8px; }
  .continuous-audio-head { align-items: flex-start; margin-bottom: 14px; }
  .continuous-audio-head h2 { font-size: 20px; }
  .continuous-audio-head-actions { gap: 18px; font-size: 15px; }
  .continuous-audio-card { min-height: min(440px,62vh); padding: 46px 34px 74px; border-radius: 8px; }
  .continuous-audio-copy { gap: 16px; }
  .continuous-audio-copy strong { font-size: clamp(42px,13vw,64px); }
  .continuous-audio-copy [data-continuous-audio-ipa],
  .continuous-audio-copy [data-continuous-audio-chinese] { font-size: clamp(22px,6vw,29px); }
  .continuous-audio-toggle { right: 18px; bottom: 18px; width: 42px; height: 42px; }
  .continuous-audio-toggle img { width: 21px; height: 21px; }
}