/* Reading and navigation take priority over optional exploration. */
[hidden] { display:none!important; }
.nav-icon { display:none; }
.nav-badge { font-size:12px; margin-inline-start:5px; }
#sync-note { min-height:44px; }
.library-intro { padding-block:12px 8px; }
.library-intro h1 { font-size:clamp(30px,4vw,46px); margin:0 0 8px; }
.library-intro p { margin:0 0 18px; font-size:17px; }
.library-intro .eyebrow { margin-bottom:8px; }
.resume-card { display:flex; align-items:center; justify-content:space-between; width:100%; max-width:730px; gap:18px; padding:16px 20px; margin:8px 0 24px; text-align:start; background:#25344d; border-inline-start:3px solid var(--bronze); }
.resume-card small,.resume-card strong { display:block; }
.resume-card small { font-size:13px; color:#c4cedd; margin-bottom:2px; }
.resume-card strong { font-size:20px; font-weight:600; }
.resume-card>span:last-child { color:var(--bronze); font-size:24px; }
.subject-content .subject-code { margin-bottom:12px; }
.library-shortcuts { display:flex; gap:10px; margin-block:28px 16px; flex-wrap:wrap; }
.library-shortcuts button { font-size:15px; }
.lecture-facts { margin:12px 0 16px; border-block:1px solid var(--library-rule); }
.lecture-facts>summary { display:flex; align-items:center; justify-content:space-between; gap:12px; padding:12px 0; min-height:46px; font-size:15px; }
.lecture-facts>summary::after { content:'+'; font-size:22px; }
.lecture-facts[open]>summary::after { content:'−'; }
.lecture-facts>summary>span { margin-inline-start:auto; font-size:13px; color:var(--muted); }
.lecture-facts .lecture-metadata { margin-block:12px 20px; }
.source-disclosure { margin-bottom:22px; }
.source-disclosure summary { min-height:44px; padding-block:8px; }
.source-disclosure p { padding:12px 0; }
.site-footer details { max-width:55ch; font-size:13px; }
.site-footer summary { min-height:44px; padding-block:10px; }
.site-footer details p { margin-top:8px; }
.lesson-reference { margin-top:12px; }
.optional-scene { align-self:start; min-width:0; }
.optional-scene summary { min-height:48px; padding:14px 18px; font-size:16px; }
.optional-scene:not([open]) { align-self:start; }
.study-layout>.optional-scene .stage-world { position:relative; top:auto; }
.reading-help summary { min-height:44px; padding-block:9px; }
body[data-view=exams] #app>p,body[data-view=review] #app>p { max-width:60ch; }

@media(max-width:760px) {
  html { scroll-padding-block:16px 90px; }
  body { font-size:17px; padding-bottom:calc(74px + env(safe-area-inset-bottom)); }
  body.auth-gate { padding-bottom:0; }
  main,.auth-gate main { padding:20px 16px 28px; width:100%; min-width:0; }
  #app>* { min-width:0; }
  h1 { font-size:30px; line-height:1.4; margin-bottom:10px; }
  h2 { font-size:23px; line-height:1.5; }
  h3 { font-size:20px; }
  p { line-height:1.85; }
  button,input,select,textarea { font-size:16px; border-radius:6px; }
  button,input:not([type=checkbox]),select { min-height:46px; }
  button { padding:10px 14px; }
  button,a,summary { -webkit-tap-highlight-color:#d2ba9622; }
  summary { cursor:pointer; min-height:44px; }
  header,.auth-gate header { height:auto; min-height:72px; padding:12px 16px; gap:8px; flex-wrap:nowrap; }
  .brand { flex:none; font-size:25px; gap:8px; min-height:44px; }
  .brand-mark { height:34px; width:34px; font-size:26px; }
  .brand small { display:none; }
  .account-header { gap:6px; margin-inline-start:auto; margin-right:0; min-width:0; }
  .account-header #account-entry { font-size:13px; padding:8px 10px; max-width:115px; overflow:hidden; text-overflow:ellipsis; }
  .display-settings>summary { font-size:13px; min-height:44px; padding:10px; }
  .settings-menu { position:absolute; width:min(280px,calc(100vw - 32px)); inset-inline-end:0; z-index:25; }
  .settings-menu button { min-height:46px; text-align:start; }
  header nav { position:fixed; z-index:20; inset:auto 0 0; display:grid; grid-template-columns:repeat(4,minmax(0,1fr)); gap:2px; width:auto; padding:6px 8px calc(6px + env(safe-area-inset-bottom)); background:#111b2c; border-top:1px solid #3a475e; box-shadow:0 -4px 18px #00000018; }
  header nav button { position:relative; display:flex; flex-direction:column; justify-content:center; align-items:center; gap:3px; min-height:56px; min-width:0; padding:6px 2px; border:0; font-size:12px; line-height:1.4; color:#aebdd1; border-radius:5px; }
  header nav button:first-child { grid-column:auto; }
  header nav button.active { background:#28364c; color:#efd6b0; border:0; }
  .nav-icon { display:block; width:21px; height:21px; flex:none; }
  .nav-badge { position:absolute; top:4px; inset-inline-end:14px; margin:0; min-width:16px; padding:1px 4px; background:#d2ba96; color:#152033; border-radius:4px; font-size:10px; }
  header nav #updates { display:none; }
  .auth-gate header nav { display:none; }
  body:has(input:focus,textarea:focus) header nav { display:none; }
  #sync-note { font-size:12px; line-height:1.6; padding:9px 16px; margin:0; width:100%; min-height:44px; text-align:start; background:#182234; }
  .library-intro { padding:0; }
  .library-intro .eyebrow { font-size:12px; margin-bottom:6px; }
  .library-intro h1 { font-size:31px; }
  .library-intro p { font-size:15px; margin-bottom:18px; }
  .resume-card { margin:0 0 22px; padding:12px 15px; }
  .resume-card strong { font-size:19px; }
  .subject-search { margin:0; }
  .subject-search label { display:block; font-size:14px; margin-bottom:7px; }
  .subject-search input { min-height:48px; font-size:16px; padding:12px; width:100%; }
  .section-top { margin:22px 0 12px; gap:12px; }
  .section-top h2 { font-size:22px; }
  .subject-grid { gap:12px; }
  .subject-card { grid-template-columns:40px minmax(0,1fr); }
  .subject-glyph { font-size:25px; }
  .subject-content { padding:13px 15px 0; }
  .subject-content h3 { font-size:21px; line-height:1.4; margin:0; }
  .subject-content .subject-code { font-size:12px; margin:3px 0 9px; display:block; }
  .subject-meta { font-size:12px; gap:4px 12px; margin-bottom:9px; }
  .subject-open { margin:10px -15px 0; width:calc(100% + 30px); padding:9px 15px; min-height:44px; font-size:14px; }
  .library-shortcuts { display:grid; grid-template-columns:1fr 1fr; gap:8px; margin:22px 0 14px; }
  .library-shortcuts button { font-size:14px; }
  .library-shortcuts button:last-child { grid-column:1/-1; }
  .explore-world>summary { font-size:14px; padding:12px; }
  .breadcrumb { margin-bottom:14px; font-size:12px; gap:8px 14px; }
  .breadcrumb button { font-size:14px; padding:8px 12px; }
  .breadcrumb .source-link { display:inline-flex; align-items:center; min-height:44px; font-size:13px; }
  .library-heading { margin-bottom:12px; padding:0 0 14px; gap:16px; }
  .library-heading h1 { font-size:29px; }
  .library-heading .subject-english { font-size:16px; margin-bottom:8px; }
  .library-heading p:last-child { font-size:15px; }
  .library-heading .heading-glyph { font-size:36px; }
  .library-record { padding:18px 16px; }
  .record-category { margin-bottom:7px; }
  .library-record h2 { font-size:23px; line-height:1.5; }
  .library-record .lecture-english { font-size:14px; margin-bottom:12px; }
  .lecture-facts { margin:10px 0 14px; }
  .lecture-facts>summary { font-size:14px; }
  .lecture-facts>summary>span { font-size:12px; }
  .lecture-metadata { gap:14px; }
  .record-footer { padding-top:0; gap:13px; border:0; }
  .record-progress>span { font-size:12px; margin-bottom:7px; }
  .course-title { margin-bottom:18px; }
  .course-title h1 { font-size:27px; }
  .course-title>.lecture-english { font-size:15px; margin-bottom:10px; }
  .course-title>p:not(.lecture-english) { font-size:15px; margin-bottom:10px; }
  .overview { grid-template-columns:minmax(0,1fr); gap:22px; }
  .lesson-list { gap:10px; }
  .lesson-row { display:grid; grid-template-columns:28px minmax(0,1fr); gap:8px 12px; padding:15px; align-items:start; }
  .lesson-row .index { font-size:18px; }
  .lesson-row>div { min-width:0; }
  .lesson-row h3 { font-size:19px; margin-bottom:4px; line-height:1.6; }
  .lesson-row p { font-size:14px; margin-bottom:0; overflow-wrap:anywhere; }
  .lesson-row .lesson-subtitle { gap:2px; }
  .lesson-row>button,.lesson-row>a { grid-column:2; margin:0; width:100%; min-height:44px; }
  .lesson-row>a { display:flex; align-items:center; font-size:14px; }
  .side-note { padding:20px; }
  .side-note h3 { font-size:23px; }
  .side-note button,.side-note>a { display:flex; justify-content:center; align-items:center; width:100%; min-height:46px; margin-block:10px; }
  .side-note p { font-size:14px; }
  .study-layout,.study-layout.tutor-layout { grid-template-columns:minmax(0,1fr); gap:14px; }
  .study-panel { padding:18px 16px; border-radius:6px; min-width:0; width:100%; }
  .study-panel h2 { font-size:25px; line-height:1.5; }
  .lesson-kicker { gap:12px; align-items:center; flex-wrap:wrap; }
  .lesson-tools { gap:6px; }
  .lesson-tools button,.lesson-tools .tiny { font-size:13px; min-height:44px; padding:8px 10px; }
  .steps { margin:12px 0 18px; gap:4px; }
  .steps span { padding:8px 3px; font-size:12px; min-width:0; }
  .teaching-path { margin-bottom:10px; }
  .teaching-path span { font-size:12px; }
  #lesson-content>.eyebrow { margin-bottom:6px; font-size:13px; }
  .example-position { margin:10px 0 12px; font-size:12px; }
  .explain,.tutor-layout .explain { font-size:21px; line-height:1.95; margin-bottom:18px; }
  .micro-note { font-size:13px!important; margin-bottom:12px; }
  .narration { margin-top:14px; }
  .narration-player { margin:8px 0 12px; }
  .narration-player audio { width:100%; max-width:100%; min-width:0; display:block; }
  .bottom-actions { gap:8px; margin-top:18px; display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); }
  .bottom-actions button { font-size:14px; width:100%; }
  .bottom-actions .primary,.bottom-actions button:only-child { grid-column:1/-1; min-height:50px; font-size:16px; }
  .lesson-feedback { margin-top:18px; padding-top:12px; }
  .lesson-feedback button { font-size:13px; min-height:44px; }
  .optional-scene summary { font-size:15px; padding:13px 15px; }
  .stage-world { height:auto; min-height:360px; position:relative; top:auto; border-radius:5px; }
  .stage-world .scene { height:300px; min-height:240px; }
  .stage-controls { position:static; padding:0 12px 12px; gap:6px; }
  .stage-controls button { min-height:44px; font-size:13px; }
  .binary-switches { grid-template-columns:repeat(4,minmax(0,1fr)); gap:8px; }
  .stage-caption { top:12px; right:15px; }
  .question { font-size:21px; line-height:1.8; overflow-wrap:anywhere; }
  .question.en { font-size:20px; text-align:left; }
  .answer-grid { gap:10px; margin-block:18px; }
  .answer { padding:13px; min-height:54px; font-size:17px; gap:12px; line-height:1.7; }
  .answer .key { flex:none; font-size:13px; }
  .answer>span:last-child { min-width:0; overflow-wrap:anywhere; }
  .answer.correct:disabled,.answer.wrong:disabled { opacity:1; }
  .feedback { padding:16px; font-size:16px; line-height:1.9; margin-top:16px; }
  #question-next { width:100%; min-height:50px; }
  .formula { font-size:21px; overflow-wrap:anywhere; }
  .micro-animation { gap:5px; }
  .micro-animation span { min-width:0; padding:9px; overflow-wrap:anywhere; font-size:17px; }
  .vocab-inline { flex-direction:column; }
  .vocab-inline button { padding:12px 14px; min-height:58px; }
  .exam-language { gap:8px; margin:20px 0; }
  .exam-language select { max-width:100%; width:100%; font-size:16px; }
  .lecture-grid:not(.library-records) { grid-template-columns:minmax(0,1fr); gap:12px; }
  .lecture-card:not(.library-record) { padding:19px 16px; border-radius:6px; }
  .lecture-card h2 { font-size:22px; }
  .lecture-card .eyebrow { margin-bottom:8px; }
  .lecture-card button { min-height:48px; width:100%; }
  .exam-wrap { width:100%; }
  .filters { display:grid; grid-template-columns:minmax(0,1fr); gap:10px; margin-block:20px; }
  .filters>* { width:100%; min-width:0; }
  .glossary-grid { grid-template-columns:minmax(0,1fr); gap:12px; }
  .word-card { padding:18px; border-radius:6px; }
  .word-card h3 { font-size:23px; overflow-wrap:anywhere; margin-block:9px 4px; }
  .word-card p { font-size:17px; margin-bottom:10px; }
  .word-card button { min-height:44px; }
  .word-test { max-width:none; margin:0; }
  .empty { padding:26px 18px; margin-top:20px; border-radius:6px; }
  .empty h2 { font-size:23px; }
  .result { padding:20px 0; }
  .result h1 { font-size:29px; overflow-wrap:anywhere; }
  .result .hero-actions { flex-direction:column; }
  .summary-strip { flex-wrap:wrap; gap:8px; }
  .auth-layout { margin:0; gap:18px; }
  .auth-story { padding:0; }
  .auth-story>.eyebrow { display:none; }
  .auth-story h1 { font-size:29px; margin:0 0 7px; line-height:1.4; }
  .auth-story h1 br { display:none; }
  .auth-story>p { font-size:15px; }
  .auth-card { padding:20px 16px; border-radius:6px; }
  .auth-card h2 { font-size:24px; margin:18px 0 4px; }
  .auth-card>p { font-size:14px; }
  .auth-tabs { gap:24px; }
  .auth-tabs button { min-height:44px; font-size:16px; }
  .auth-card label { font-size:16px; margin-top:12px; }
  .auth-card input:not([type=checkbox]),.password-field input { min-height:48px; font-size:16px; }
  .form-status:empty { min-height:0; margin:10px 0; }
  .recover-link { min-height:44px; margin:10px 0 4px; }
  .guest-entry { margin-top:10px; }
  .auth-card .account-note { margin-top:13px; font-size:12px!important; }
  .check-label { align-items:center!important; }
  .check-label input { flex:none; width:22px; height:22px; }
  .check-label .text-button { min-height:44px; }
  dialog,.account-dialog { max-height:85dvh; max-width:calc(100vw - 24px); width:calc(100vw - 24px); padding:22px 18px; border-radius:8px; overflow-y:auto; overscroll-behavior:contain; }
  dialog h2,.account-dialog h2 { font-size:25px; }
  dialog p { font-size:16px; line-height:1.85; }
  dialog select { width:100%; }
  .close-dialog { min-width:44px; min-height:44px; }
  .account-dialog input:not([type=checkbox]),.account-dialog select,.account-dialog textarea { font-size:16px; }
  .table-scroll { width:100%; overflow-x:auto; }
  .truth-table { min-width:0; width:100%; }
  .truth-table th,.truth-table td { padding:10px 4px; font-size:14px; }
  .truth-table select { min-width:64px; font-size:16px; padding:7px; }
  .writing-editor .steps { flex-wrap:wrap; }
  .writing-editor .steps button { flex:1 1 40%; font-size:14px; }
  .writing-editor textarea { font-size:18px; line-height:1.9; font-family:inherit; width:100%; padding:12px; }
  body[data-view=library] .lesson-row { grid-template-columns:1fr 1fr; }
  body[data-view=library] .lesson-row>.index { display:none; }
  body[data-view=library] .lesson-row>div { grid-column:1/-1; }
  body[data-view=library] .lesson-row>a { grid-column:1; }
  body[data-view=library] .lesson-row>button { grid-column:2; }
  .update-entry { padding:20px 16px; margin-block:16px; border-radius:6px; }
  .update-entry h2 { font-size:23px; }
  .update-entry ul { font-size:16px; line-height:1.9; }
  .site-footer { display:block; margin-top:0; padding:22px 16px 18px; }
  .site-footer strong { font-size:19px; }
  .site-footer p { font-size:12px; margin:4px 0; }
  .site-footer summary { font-size:12px; }
  #toast { bottom:calc(85px + env(safe-area-inset-bottom)); max-width:calc(100vw - 32px); width:max-content; white-space:normal; font-size:14px; }
}
@media(max-width:359px) {
  header { padding-inline:12px; }
  main { padding-inline:12px; }
  .brand { font-size:22px; gap:5px; }
  .brand-mark { width:28px; height:32px; }
  .account-header #account-entry { font-size:12px; max-width:104px; }
  .display-settings>summary { padding:10px 7px; font-size:12px; }
  .study-panel { padding:16px 13px; }
  .explain,.tutor-layout .explain { font-size:20px; }
}
@media(prefers-reduced-motion:reduce) {
  .subject-card:hover { transform:none; }
}