.chapter-shell{--chapter-bg:#f7f9fc;--chapter-panel:#fff;--chapter-text:#192c40;--chapter-muted:#50637a;--chapter-border:#cad6e3;--chapter-accent:#0f6670;background:var(--chapter-bg);color:var(--chapter-text);min-height:75vh;padding:24px;border-radius:16px;max-width:1120px;margin:auto}.chapter-shell.dark{--chapter-bg:#14212e;--chapter-panel:#1c3040;--chapter-text:#edf4fb;--chapter-muted:#bdcddd;--chapter-border:#587184;--chapter-accent:#8cdbd5}.chapter-shell h1{font-size:clamp(1.8rem,4vw,2.8rem);line-height:1.2;margin:12px 0}.chapter-shell h2{font-size:1.4rem}.chapter-shell h3{font-size:1.1rem;margin:0}.chapter-shell p{line-height:1.65}.chapter-shell a{color:var(--chapter-accent)}.chapter-header,.chapter-levels,.chapter-section-title,.chapter-tools,.lesson-steps{display:flex;align-items:center;gap:12px;flex-wrap:wrap}.chapter-header{justify-content:space-between}.chapter-header a{text-decoration:none}.chapter-levels button,.chapter-tools button,.lesson-steps 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textarea{border:1px solid var(--chapter-border);border-radius:6px;background:var(--chapter-panel);color:var(--chapter-text);padding:12px;font:inherit;max-width:100%}.chapter-speed select{width:auto}.chapter-word-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));grid-gap:12px;gap:12px;margin:24px 0}.chapter-explanation,.chapter-question,.chapter-summary,.chapter-word{padding:20px;border:1px solid var(--chapter-border);border-radius:10px;background:var(--chapter-panel)}.chapter-question{margin:24px 0;min-width:0}.chapter-question legend{padding:0 6px;font-weight:600;max-width:100%;white-space:normal}.chapter-question :is(input:not([type=checkbox]),textarea,select){display:block;width:100%;margin:12px 0}.chapter-model{margin-top:16px;border-left:3px solid var(--chapter-accent);padding:4px 0 4px 16px}.chapter-audio label,.chapter-model label{display:flex;gap:10px;align-items:flex-start;line-height:1.5;margin:14px 0}.chapter-audio input,.chapter-model 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(max-width:650px){.chapter-shell{padding:16px;border-radius:0}.chapter-header{align-items:flex-start}.chapter-tools{gap:6px}.chapter-tools button{padding:8px}.chapter-list li{grid-template-columns:30px minmax(0,1fr);padding:16px;gap:10px}.chapter-list li>button{grid-column:2;justify-self:start}.chapter-word-grid{grid-template-columns:1fr}.chapter-question{padding:14px}.chapter-shell h1{overflow-wrap:anywhere}.lesson-steps{gap:6px}.lesson-steps button{padding:10px}.chapter-section-title .primary{width:100%}}.chapter-audio-settings{display:grid;grid-template-columns:minmax(0,2fr) minmax(120px,1fr);grid-gap:16px;gap:16px;margin:20px 0}.chapter-audio-settings label{display:flex;flex-direction:column;gap:8px;align-items:flex-start}.chapter-audio-settings select{width:100%;min-width:0}.chapter-lesson textarea{display:block;width:100%;margin:12px 0}.chapter-lesson section>label{display:block;margin-top:18px;font-weight:600}.chapter-word details{margin:12px 0}.chapter-word summary{cursor:pointer;color:var(--chapter-accent)}.chapter-lesson .chapter-question input,.chapter-lesson .chapter-question select{min-height:46px}@media(max-width:650px){.chapter-audio-settings{grid-template-columns:1fr}.chapter-audio-settings .chapter-speed{margin:0}}