:root{--bg:#FAFAF7;--surface:#FFFFFF;--warm:#FFF8F1;--ink:#1A1410;--muted:#6B5D54;--line:#EFE8DF;--orange:#FF6B35;--deep:#C44A1F;--hover:#E85A24;--peach:#FFE5D4;--green:#2D5F3F;--sage:#E8F0EA;--copper:#B7603E}
[hidden]{display:none!important}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:100px}body{margin:0;background:var(--bg);color:var(--ink);font-family:"PingFang TC","Noto Sans TC","Microsoft JhengHei",sans-serif;-webkit-font-smoothing:antialiased}button,input,a{-webkit-tap-highlight-color:transparent}a{color:inherit;text-decoration:none}button,input{font:inherit}button,a,input,summary{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:default;opacity:.5}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--green);outline-offset:4px}button{color:var(--ink)}p{margin:0}h1,h2,h3{margin:0;font-weight:600}button{border:0}svg{display:block}section{scroll-margin-top:98px}.skip{position:fixed;left:16px;top:-100px;background:var(--green);color:var(--surface);padding:12px;z-index:100}.skip:focus{top:12px}.site-header{height:78px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 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var(--copper);border-radius:8px;padding:10px 15px;font-size:23px;background:var(--warm);color:var(--ink)}.quiz-actions{display:flex;align-items:center;gap:20px;justify-content:space-between;margin-top:23px;flex-wrap:wrap}.hint-text{padding:15px 18px;background:var(--warm);color:var(--muted);border-radius:8px;font-size:14px;line-height:1.8;margin-top:18px}.quiz-feedback{margin-top:20px;background:var(--sage);border-radius:10px;padding:18px 20px;font-size:14px;line-height:1.9;color:var(--green)}.quiz-feedback.wrong{background:var(--warm);color:var(--deep)}.quiz-feedback strong{display:block;font-size:15px;margin-bottom:4px}.quiz-feedback p{color:var(--ink)}.validation{font-size:13px;color:var(--deep);margin-top:13px}.save-status{font-size:10px;color:var(--muted);padding:0 33px 19px;line-height:1.8}.result-heading{font-size:25px;line-height:1.7}.result-intro{font-size:14px;line-height:1.9;color:var(--muted);margin-top:11px}.result-stats{display:flex;gap:35px;margin:25px 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@media(max-width:1150px){.course-layout{grid-template-columns:205px minmax(0,1fr);padding:0 26px}.course-rail{padding-right:16px}main{padding-left:30px}.hero-copy h1{font-size:44px}.hero-question{font-size:20px}.hero-art{padding:24px 14px}.hero-blocks{gap:5px}.art-equation{gap:12px;font-size:30px}.lab-body{grid-template-columns:minmax(0,1fr) 210px}.lab-controls{padding:22px 16px}.pair-notebook{gap:17px}.section-heading h2{font-size:23px}.takeaway{grid-template-columns:1fr 155px;padding:28px}.takeaway-side{padding-left:20px}.takeaway-equation{font-size:12px}.answer-options.multi{grid-template-columns:repeat(3,1fr)}}
@media(max-width:850px){.site-header{height:68px;padding:0 24px}.course-layout{display:block;padding:0 26px}.course-rail{display:none}main{padding:25px 0 0;max-width:820px;margin:auto}.lesson-hero{gap:35px}.hero-copy h1{font-size:52px}.hero-question{font-size:22px}.lab-body{grid-template-columns:minmax(0,1fr) 240px}.lab-controls{padding:24px}.hero-art{padding:25px 20px}.hero-blocks{gap:7px}.answer-options.multi{grid-template-columns:repeat(4,1fr)}}
@media(max-width:580px){html{scroll-padding-top:83px}.site-header{height:64px;padding:0 18px}.brand{font-size:19px;gap:9px}.brand img{width:30px;height:30px;border-radius:7px}.brand-divider{margin:0 1px;height:17px}.brand-course{font-size:12px}.preview-label{font-size:9px;gap:5px}.preview-label>span{width:4px;height:4px}.course-layout{padding:0 20px}main{padding-top:22px}.breadcrumb{font-size:10px;gap:8px;margin-bottom:26px}.lesson-hero{grid-template-columns:1fr;gap:25px}.hero-copy h1{font-size:46px;margin:11px 0 12px}.hero-question{font-size:23px}.hero-summary{font-size:15px;margin:13px 0 19px}.hero-copy .primary{width:100%;justify-content:space-between}.lesson-meta{font-size:10px}.hero-art{padding:23px 24px 24px;display:grid;grid-template-columns:1fr 1fr;column-gap:22px;align-items:center;text-align:left}.art-tag{grid-column:1/-1;justify-self:start;margin-bottom:20px}.hero-blocks{grid-row:2/5;width:100%;gap:4px;padding:0}.hero-blocks span{border-radius:3px}.art-equation{font-size:26px;gap:10px;margin-top:0;justify-content:start}.art-equation i{font-size:17px}.hero-art>p{font-size:10px;line-height:1.8}.art-note{font-size:10px;line-height:1.8;margin-top:8px}.goal-strip{gap:12px;padding:17px 0}.goal-strip p,.goal-strip strong{font-size:12px}.lesson-section{margin-top:48px}.section-heading{gap:13px}.section-number{font-size:34px}.section-heading h2{font-size:22px}.eyebrow{font-size:10px}.section-intro{font-size:15px;margin:15px 0 21px}.lab-header{padding:16px 18px}.lab-total{font-size:10px}.lab-body{grid-template-columns:1fr}.board-wrap{padding:14px 10px 5px;min-height:220px}#block-board{max-height:245px}.board-caption{font-size:11px}.lab-controls{padding:20px 21px}.stepper{margin:12px 0 8px}.stepper button{width:42px;height:42px}.stepper output{font-size:33px}.lab-controls>label{font-size:14px}.quick-choices{gap:8px}.quick-choices button{font-size:12px;min-width:43px;min-height:38px}.quick-label{margin-top:13px}.division-feedback{min-height:0;margin:17px 0 14px}.division-feedback strong{font-size:23px}.lab-controls .small-text{min-height:0}.pair-notebook{padding:19px 20px;gap:15px}.pair-notebook>div:first-child{flex-basis:100%;display:flex;justify-content:space-between;gap:10px;align-items:center}.pair-notebook p{margin:0}.pairs-list{gap:5px}.pair-slot{min-width:51px;padding:9px 7px;font-size:15px}.pair-notebook>.text-button{font-size:10px}.reflection summary{font-size:13px}.reflection p{font-size:14px}.definition{font-size:18px;margin:22px 0;line-height:1.85}.compare-grid{gap:10px}.compare-card{padding:20px 14px}.math-line{font-size:22px;margin:18px 0}.math-line small{font-size:12px}.compare-card h3{font-size:14px;line-height:1.8}.compare-card>p:last-child{font-size:11px}.key-thought{gap:12px}.key-thought p{font-size:14px}.worked-example{padding:23px 22px;margin-top:22px}.worked-example h3{font-size:22px}.worked-example>p{font-size:15px}.example-label{font-size:11px}.example-label span{margin-left:10px}.example-pairs{gap:7px}.example-pair{min-width:0;flex:1;padding:15px 9px;font-size:24px;text-align:center}.example-pair.hidden-pair{font-size:20px}.practice-header{padding:17px 20px;flex-wrap:wrap;gap:13px}.practice-header .mini-label{font-size:11px}#question-nav{gap:6px}#question-nav button{width:31px;height:31px}#quiz-content{padding:24px 22px 18px}.question-title{font-size:20px}.answer-options{gap:9px}.answer-option{font-size:16px;padding:13px 14px;gap:11px}.answer-options.multi{grid-template-columns:1fr 1fr}.answer-options.multi .answer-option{padding:14px}.quiz-feedback{padding:15px;font-size:13px}.quiz-actions{gap:12px}.quiz-actions .primary{font-size:13px;padding:12px 17px}.quiz-actions .text-button{font-size:11px}.save-status{padding:0 22px 20px;font-size:10px}.takeaway{margin-top:48px;grid-template-columns:1fr;gap:26px;padding:27px 24px}.takeaway h2{font-size:24px}.takeaway-side{border-left:0;border-top:1px solid #2D5F3F26;padding:22px 0 0}.takeaway-side h3{font-size:21px}.takeaway-side h3 br{display:none}.takeaway-equation{font-size:13px}.lesson-footer{margin-top:40px}.result-heading{font-size:23px}.result-stats{gap:23px}.review-list button{font-size:12px;padding:13px 12px}.review-list button span{font-size:10px}.lesson-end .secondary{font-size:12px;padding:11px 14px}.lesson-end .text-button{font-size:11px}}
@media(max-width:350px){.course-layout{padding:0 16px}.site-header{padding:0 14px}.brand-divider,.brand-course{display:none}.preview-label{font-size:9px}.hero-art{padding:20px 17px;gap:14px}.art-equation{font-size:22px;gap:7px}.hero-copy h1{font-size:42px}.section-heading h2{font-size:20px}.compare-card{padding:17px 12px}.math-line{font-size:19px}.pair-slot{min-width:47px;font-size:13px}.pair-notebook{padding:18px 15px}.practice-header{padding:17px}.question-title{font-size:18px}#quiz-content{padding:22px 18px}.save-status{padding-left:18px}.takeaway{padding:25px 21px}.takeaway h2{font-size:22px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important}}
@media print{.site-header,.course-rail,.breadcrumb,.hero-copy .primary,.lab-controls,.pair-notebook>button,.lesson-end,.practice-card,.lesson-meta{display:none}.course-layout{display:block;padding:0}main{padding:0}.lesson-section{margin-top:28px}.lesson-hero{gap:20px}.hero-copy h1{font-size:34px}.hero-question{font-size:19px}.hero-art{break-inside:avoid}.lab-body{grid-template-columns:1fr}.lesson-footer{margin-top:25px}.worked-example,.compare-card,.takeaway{break-inside:avoid}details:not([open]){display:none}body{background:var(--surface)}}
/* LC-04: retain the approved warm style, add two-lesson navigation and child-readable controls. */
:root{--copper-deep:#8F432A}
.eyebrow,.mini-label,.art-tag{color:var(--copper-deep)}
.primary:hover{background:var(--copper-deep)}
.lesson-switch{display:flex;gap:8px;flex-wrap:wrap;margin:0 0 28px}
.lesson-switch a{display:flex;align-items:center;min-height:44px;padding:10px 15px;border-radius:8px;background:var(--surface);border:1px solid var(--line);font-size:14px;line-height:1.6}
.lesson-switch a[aria-current=page]{background:var(--peach);border-color:var(--peach);color:var(--deep);font-weight:600}
.next-lessons a{min-height:44px;display:flex;align-items:center;color:var(--ink);line-height:1.7}
.next-lessons a[aria-current=page]{color:var(--deep);font-weight:600}
.mobile-contents{display:none;margin-bottom:26px;border-bottom:1px solid var(--line)}
.mobile-contents summary{padding:12px 0;min-height:44px;display:flex;align-items:center;justify-content:space-between;font-size:14px}
.mobile-contents nav{display:grid;padding:6px 0 12px}.mobile-contents nav a{display:flex;align-items:center;min-height:44px;font-size:14px;color:var(--muted)}
.lab-total,.mini-label,.quick-label,.board-caption,.art-note,.hero-art>p{font-size:14px}
.lab-controls>label{font-size:16px}.quick-choices{gap:6px}.quick-choices button{min-width:44px;min-height:44px;font-size:14px}
.stepper button{width:44px;height:44px}.division-feedback{font-size:14px;line-height:1.9}.collect{font-size:14px;min-height:44px}
.lab-controls .small-text{font-size:13px}.pair-notebook h3{font-size:14px}.pair-notebook p{font-size:15px;line-height:1.9;margin:0;flex:1;min-width:190px}
.text-button{min-height:44px;font-size:14px}.reflection summary,.solution summary{min-height:44px;font-size:15px}
#question-nav button{min-width:44px;min-height:44px;font-size:16px}
.quiz-primary-actions{display:flex;gap:10px;flex-wrap:wrap}.quiz-actions .primary,.quiz-actions .secondary{min-height:44px}
.answer-options.long-options{grid-template-columns:1fr}.answer-option{min-height:56px;line-height:1.8}
.question-title,#answer-feedback,#practice-result-title,#exit-heading,#exit-result{scroll-margin-top:100px}
.question-label,.question-instruction{font-size:14px;line-height:1.9}.hint-text,.quiz-feedback{font-size:15px}.save-status{font-size:12px}
.seen-notice{font-size:14px;line-height:1.9;padding:12px 15px;margin-top:14px;border-radius:8px;background:var(--warm);color:var(--muted)}
.factor-answer{display:block}.factor-answer label{display:block;margin-bottom:10px}.factor-answer input{width:100%;font-size:18px;min-height:52px}
.result-stat p{font-size:13px;line-height:1.8}.review-list button{font-size:14px;min-height:48px}.review-list button span{font-size:12px}
.enumeration-body{padding:26px}.candidate-panel h3{font-size:23px;line-height:1.7;margin:14px 0 18px}.candidate-panel .eyebrow{font-size:14px}
.trial-feedback{font-size:16px;line-height:1.9;margin:20px 0 0;color:var(--muted);min-height:60px}
.trials-table{margin-top:22px;overflow-wrap:anywhere}.trials-table table{width:100%;border-collapse:collapse;table-layout:fixed;font-size:15px;line-height:1.8}
.trials-table caption{text-align:left;color:var(--muted);padding-bottom:14px;font-size:14px}.trials-table th,.trials-table td{padding:13px 11px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}
.trials-table th:first-child{width:17%}.trials-table th:nth-child(2){width:43%}.trials-table thead th{font-weight:500;background:var(--warm)}
#empty-trials{padding:22px 12px;color:var(--muted);font-size:15px}
.factor-notebook{margin-top:25px;padding-top:22px;border-top:1px solid var(--line)}.factor-notebook h3{font-size:16px;line-height:1.8}.factor-chips{display:flex;flex-wrap:wrap;gap:9px;margin:15px 0;min-height:44px}
.factor-chip{display:grid;place-items:center;min-width:42px;min-height:42px;padding:8px;background:var(--sage);border-radius:8px;font:22px Georgia,serif;color:var(--green)}
.stop-explanation{padding:18px 20px;background:var(--sage);border-radius:10px;font-size:16px;line-height:1.9;color:var(--green);margin:20px 0 8px}
#exit-content{padding:30px 33px}.exit-items{display:grid;gap:30px}.exit-items fieldset{margin:0;padding:0 0 26px;border:0;border-bottom:1px solid var(--line);min-width:0}.exit-items legend{font-size:14px;color:var(--copper-deep);margin-bottom:16px;padding:0}.exit-items .question-title{font-size:21px}.exit-items .answer-options{margin-top:20px}
.exit-summary{margin-top:28px;padding:22px;background:var(--sage);border-radius:12px}.exit-summary h3{font-size:22px}.exit-summary p{font-size:15px;line-height:1.9;color:var(--muted);margin:13px 0 20px}
.takeaway-side .primary{margin-top:15px;font-size:13px;padding:12px}.result-intro{font-size:16px}
@media(max-width:850px){.mobile-contents{display:block}.lesson-switch a{flex:1;font-size:14px;min-width:230px}.lesson-switch{margin-bottom:10px}.hero-art{margin-top:0}}
@media(max-width:580px){.hero-art{column-gap:16px}.art-note,.hero-art>p{font-size:12px}.art-tag{font-size:12px}.section-heading h2{font-size:22px}.lab-total,.mini-label{font-size:13px}.board-caption{font-size:14px}.quick-label,.range-labels{font-size:13px}.lab-controls>label{font-size:16px}.pair-notebook>h3{flex-basis:100%;font-size:15px}.pair-notebook p{min-width:0;flex-basis:100%;font-size:15px}.pair-notebook>.text-button{font-size:14px}.worked-example>p,.reflection p{font-size:16px}.solution-steps p{font-size:16px}.practice-header{padding:17px 18px}.question-title{font-size:20px}.hint-text,.quiz-feedback{font-size:15px}.quiz-actions .text-button{font-size:14px}.save-status{font-size:12px;line-height:1.8}.result-stat p{font-size:13px}.review-list button{font-size:14px;display:block}.review-list button span{display:block;font-size:12px;margin-top:5px}.enumeration-body{padding:22px 18px}.candidate-panel h3{font-size:21px}.trials-table table{font-size:14px}.trials-table th,.trials-table td{padding:12px 6px}.trials-table th:first-child{width:16%}.trials-table th:nth-child(2){width:43%}.stop-explanation{font-size:16px;padding:17px}.factor-notebook h3{font-size:15px}#exit-content{padding:25px 20px}.exit-items .question-title{font-size:20px}.exit-items legend{font-size:14px}.takeaway-side p{font-size:14px!important}.takeaway-side h3 br{display:none}}
@media(max-width:350px){.lesson-switch a{min-width:210px}.section-heading h2{font-size:20px}.hero-copy h1{font-size:40px}.hero-art{column-gap:12px}.hero-art>p,.art-note{font-size:11px}.art-equation{gap:6px;font-size:22px}.trials-table table{font-size:13px}.trials-table th,.trials-table td{padding:12px 5px}.candidate-panel h3{font-size:19px}.question-title,.exit-items .question-title{font-size:19px}.enumeration-body{padding:20px 14px}#exit-content{padding:23px 18px}.result-stats{gap:20px}}
@media print{.lesson-switch,.mobile-contents,.practice-card,.candidate-panel button,.factor-notebook button{display:none}.trials-table{break-inside:avoid}}

/* Reviewed selected-state contrast on peach surfaces. */
.lesson-switch a[aria-current=page],.current-lesson div span,.quick-choices button[aria-pressed=true]{color:var(--copper-deep)}

/* LC-06: one course tree, shared section names, and a compact reading menu. */
html{scroll-padding-top:0;scrollbar-gutter:stable}
section,[tabindex="-1"]{scroll-margin-top:var(--reading-offset,110px)}
#question-title,#answer-feedback,#practice-result-title,#exit-heading,#exit-result{scroll-margin-top:var(--reading-offset,110px)}
.section-heading{display:block}.section-heading h2{font-size:26px;line-height:1.6}
.section-lead{font-size:18px;line-height:1.85;color:var(--muted);margin:10px 0 22px;font-weight:500}
.section-intro{margin-top:0}.takeaway .section-heading h2{margin:0 0 12px}
.takeaway .takeaway-lead{font-size:20px!important;font-weight:600;color:var(--green)!important;margin:8px 0 14px}
.course-rail{padding-top:30px}.course-rail>h2{margin:8px 0 24px}
.course-tree .tree-group-label{font-size:13px;font-weight:600;color:var(--muted);line-height:1.6;margin:0 0 10px}
.course-list,.section-links{list-style:none;margin:0;padding:0}.course-list{display:grid;gap:6px}
.course-tree .course-item{display:grid;grid-template-columns:45px minmax(0,1fr);gap:3px 8px;align-items:baseline;border:0;border-radius:8px;padding:12px 10px;min-height:56px;color:var(--ink);line-height:1.7;margin:0;font-size:14px}
.course-item>span{font-size:12px;color:var(--muted)}.course-item>strong{font-size:14px;font-weight:500;overflow-wrap:anywhere}
.course-item>small{grid-column:2;font-size:12px;color:var(--muted)}
.course-tree a.course-item:hover{background:var(--warm);color:var(--copper-deep)}
.course-tree .current-course-label{background:var(--peach)}.current-course-label>strong{font-weight:600}.current-course-label>small{color:var(--copper-deep)}
.current-course-contents{padding:16px 0 12px 16px}.current-course-contents>.tree-group-label{margin-left:11px}
.section-links{border-left:1px solid var(--line)}
.course-tree .section-links a{display:flex;align-items:center;justify-content:space-between;gap:8px;border:0;border-left:3px solid transparent;border-radius:0 6px 6px 0;margin:0 0 2px -1px;padding:10px 9px 10px 12px;min-height:44px;font-size:14px;line-height:1.6;color:var(--muted)}
.course-tree .section-links a:hover{background:var(--warm);color:var(--ink)}
.course-tree .section-links a[aria-current=location]{background:var(--warm);border-left-color:var(--copper-deep);color:var(--copper-deep);font-weight:600}
.reading-indicator{display:none;font-size:10px;font-weight:400;white-space:nowrap}.section-links a[aria-current=location] .reading-indicator{display:inline}
.future-course .course-item{border-top:1px solid var(--line);border-radius:0}.future-course .course-item>strong{color:var(--muted)}
.rail-note{margin-top:24px}.compact-lessonbar{display:none}
.course-dialog{position:fixed;inset:0 0 auto auto;padding:0;border:0;border-left:1px solid var(--line);border-radius:16px 0 0 16px;background:var(--surface);color:var(--ink);width:min(440px,calc(100vw - 24px));height:100dvh;max-height:100dvh;margin:0 0 0 auto;overflow-y:auto;overscroll-behavior:contain}
.course-dialog::backdrop{background:#1A141052}.menu-open{overflow:hidden}
.dialog-header{position:sticky;top:0;background:var(--surface);z-index:1;display:flex;align-items:center;justify-content:space-between;gap:14px;border-bottom:1px solid var(--line);padding:20px 24px}
.dialog-header h2{font-size:22px;line-height:1.5}.dialog-header p{font-size:13px;color:var(--muted);line-height:1.8;margin-top:4px}
#close-course-menu{display:grid;place-items:center;width:44px;height:44px;flex-shrink:0;background:var(--warm);border:1px solid var(--line);border-radius:12px}
.dialog-content{padding:22px 24px 32px}.course-dialog .course-item{grid-template-columns:50px minmax(0,1fr);padding:12px}.course-dialog .course-item>strong{font-size:16px}
.course-dialog .section-links a{font-size:16px;min-height:48px;padding-left:14px}.course-dialog .reading-indicator{font-size:12px}
.exit-review-links{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:12px}.exit-review-links .secondary{min-height:48px;font-size:14px;text-align:center;justify-content:center;padding:12px;line-height:1.7}
.exit-review-links a{grid-column:1/-1}.feedback-title{margin:0 0 12px;font-size:17px;font-weight:600;color:var(--ink)}.feedback-back{display:inline-flex;align-items:center;margin-top:12px;color:var(--copper-deep)}
@media(max-width:1099px){
  .course-layout{display:block;padding:0 32px}.course-rail{display:none}main{max-width:900px;margin:auto;padding:28px 0 0}
  .site-header{height:64px;padding:0 24px}.compact-lessonbar{position:sticky;top:var(--site-header-height,64px);z-index:21;display:flex;align-items:center;justify-content:space-between;gap:14px;padding:10px 32px;background:var(--bg);border-bottom:1px solid var(--line);min-height:72px}
  .compact-lessonbar>div{min-width:0}.compact-course-title{font-size:14px;line-height:1.6;font-weight:600}.compact-reading{font-size:12px;line-height:1.7;color:var(--muted);margin-top:2px}
  #open-course-menu{display:flex;align-items:center;justify-content:center;gap:7px;min-width:80px;min-height:44px;padding:10px 12px;border:1px solid var(--line);border-radius:12px;background:var(--surface);font-size:14px;flex-shrink:0}
  .hero-copy h1{font-size:48px}.hero-question{font-size:22px}.lesson-hero{gap:30px}.hero-art{padding:26px 20px}
  .lab-body{grid-template-columns:minmax(0,1fr) 240px}.section-heading h2{font-size:25px}
  .breadcrumb{margin-bottom:24px}
}
@media(min-width:600px) and (max-width:1099px){.lesson-hero{grid-template-columns:minmax(0,1fr) minmax(0,1fr)}.hero-art{align-self:center}.hero-summary{font-size:16px}.goal-strip p,.goal-strip strong{font-size:15px}.lab-controls{padding:24px}.compare-card{padding:25px}.takeaway{grid-template-columns:minmax(0,1fr) 190px}}
@media(max-width:599px){
  .course-layout{padding:0 20px}.compact-lessonbar{padding:9px 20px;gap:10px}.site-header{padding:0 18px}.compact-course-title{font-size:13px}.compact-reading{font-size:12px}#open-course-menu{min-width:76px;padding:9px;font-size:14px}
  .lesson-hero{grid-template-columns:1fr;gap:25px}.hero-copy h1{font-size:44px}.section-heading h2{font-size:24px}.section-lead{font-size:18px;margin:10px 0 20px}.lab-body{grid-template-columns:1fr}
  .takeaway{grid-template-columns:1fr;padding:26px 24px}.takeaway-side{border-left:0;border-top:1px solid #2D5F3F26;padding:22px 0 0}.takeaway-side h3{font-size:21px}.takeaway-side h3 br{display:block}
  .dialog-header{padding:16px 20px}.dialog-content{padding:20px 18px 28px}.course-dialog .course-item{grid-template-columns:46px minmax(0,1fr);gap:3px 7px}.course-dialog .section-links a{font-size:15px}.course-dialog .reading-indicator{font-size:11px}
}
@media(max-width:350px){.course-layout{padding:0 16px}.compact-lessonbar{padding-left:16px;padding-right:16px}.compact-course-title{font-size:12px}.hero-copy h1{font-size:40px}.section-heading h2{font-size:23px}.exit-review-links{grid-template-columns:1fr}.exit-review-links a{grid-column:auto}.dialog-header{padding:14px 16px}.dialog-content{padding:18px 14px}.course-dialog .section-links a{padding-left:10px}.course-dialog .reading-indicator{font-size:10px}}
@media(max-height:500px) and (max-width:1099px){.compact-lessonbar{min-height:56px;padding-top:5px;padding-bottom:5px}.compact-reading{display:none}.dialog-header{padding-top:10px;padding-bottom:10px}}
@media print{.compact-lessonbar,.course-dialog,.exit-review-links,.feedback-back{display:none!important}.course-layout{padding:0}main{max-width:none}.section-heading h2{font-size:22px}}
/* Old number-span decoration must not restyle the new text navigation. */
.course-tree .section-links a>span{font:inherit;color:inherit}
.course-tree .course-item>span{font:inherit;font-size:12px;color:var(--muted)}
/* Keep scroll-into-view targets clear of the drawer's sticky heading. */
.course-dialog{scroll-padding-block:110px 20px}

/* LC-07: six-question navigation wraps within the card on small screens. */
.practice-header{flex-wrap:wrap}#question-nav{flex-wrap:wrap;max-width:100%}
@media(max-width:399px){body[data-lesson="4N3-03"] #question-nav,body[data-lesson="4N3-04"] #question-nav{display:grid;grid-template-columns:repeat(3,44px)}body[data-lesson="4N3-03"] .practice-header,body[data-lesson="4N3-04"] .practice-header{align-items:flex-start}}

/* LC-08: unit review has no lesson numeral; keep six-item navigation compact. */
.course-tree .review-course-item{grid-template-columns:1fr;border-top:1px solid var(--line)}
.course-tree .review-course-item>small{grid-column:1}
@media(max-width:399px){body[data-lesson="4N3-05"] #question-nav,body[data-lesson="4N3-06"] #question-nav{display:grid;grid-template-columns:repeat(3,44px)}body[data-lesson="4N3-05"] .practice-header,body[data-lesson="4N3-06"] .practice-header{align-items:flex-start}}

/* LC-09: separate units without a second ambiguous lesson numbering level. */
.planned-course{color:var(--muted);border:1px dashed var(--line);margin-top:6px;opacity:1}
.planned-course small{grid-column:2;font-size:12px;font-weight:400;line-height:1.6}
.unit-switch{border-top:1px solid var(--line);padding-top:22px;margin-top:26px;display:grid;gap:10px}
.course-tree .unit-switch>a,.course-tree .unit-switch>span{display:block;padding:12px;border-radius:12px;font-size:15px;line-height:1.65;overflow-wrap:anywhere}
.course-tree .unit-switch>a{border:1px solid var(--line);background:var(--surface)}
.course-tree .unit-switch>span{background:var(--peach);color:var(--copper-deep)}
.unit-switch small{display:block;font-size:12px;color:var(--muted);font-weight:400}
body[data-lesson^="4N4-"] #question-nav{flex-wrap:wrap}
@media(max-width:480px){body[data-lesson^="4N4-"] #question-nav{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));width:100%}}

/* Original LC-18 mathematical diagrams retain their own scrollable scale. */
.audit-figure{max-width:100%;overflow-x:auto;margin:16px 0}.audit-figure figcaption{font-size:14px;line-height:1.8;color:var(--muted);padding-top:10px}.audit-figure svg{max-width:none}

.audit-table{border-collapse:collapse;min-width:420px;width:100%;margin:10px 0}.audit-table caption{text-align:left;font-size:15px;line-height:1.8;padding-bottom:10px}.audit-table th,.audit-table td{border:1px solid var(--line);padding:10px 12px;text-align:center;font-size:19px}.audit-table th{font-size:14px;font-weight:600;background:var(--warm)}.audit-table th[scope=row]{text-align:left;white-space:nowrap}