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var(--space-3);border-bottom:1px solid var(--color-border);text-align:left}.lesson-skeleton{gap:var(--space-6);max-width:760px;padding-block:var(--space-6);flex-direction:column;display:flex}.lesson-skeleton__player{aspect-ratio:16/9;border-radius:var(--radius-lg);background:var(--color-bg-muted)}.lesson-skeleton__lines{gap:var(--space-3);flex-direction:column;display:flex}.lesson-skeleton__lines i{border-radius:var(--radius-sm);background:var(--color-bg-muted);height:18px;display:block}.lesson-skeleton__lines i:first-child{width:90%;height:36px}.lesson-skeleton__lines i:last-child{width:50%}.nudge{width:min(480px, calc(100vw - 2 * var(--space-4)));border:1px solid var(--color-border);border-radius:var(--radius-xl);background:var(--color-bg-base);color:var(--color-text-primary);box-shadow:var(--shadow-xl);padding:0}.nudge::backdrop{background:#0000008c}.nudge__body{gap:var(--space-3);padding:var(--space-8) var(--space-6) var(--space-6);flex-direction:column;display:flex}.nudge 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solid var(--bright-amber);border-radius:0 var(--radius-md) var(--radius-md) 0;background:var(--color-bg-overlay);color:var(--color-text-secondary)}.lesson__why strong{color:var(--color-text-primary)}.keep-going{gap:var(--space-3);flex-direction:column;display:flex}.keep-going__links{gap:var(--space-3);grid-template-columns:repeat(auto-fit,minmax(min(260px,100%),1fr));display:grid}.keep-going__links a{padding:var(--space-4);background:var(--color-bg-surface);border:1.5px solid var(--color-border);border-radius:var(--radius-lg);color:var(--color-text-primary);transition:border-color var(--duration-fast);flex-direction:column;gap:4px;text-decoration:none;display:flex}.keep-going__links a:hover{border-color:var(--color-text-primary)}.keep-going__links .keep-going__thumb{aspect-ratio:16/9;margin-bottom:var(--space-2);border-radius:var(--radius-md);background:var(--tone-bg);display:block;position:relative;overflow:hidden}.keep-going__thumb img{object-fit:cover}.keep-going__links small{font-size:var(--text-xs);font-weight:var(--weight-bold);letter-spacing:.08em;text-transform:uppercase;color:var(--color-text-muted)}.keep-going__links b{line-height:1.35}.keep-going__links span{font-size:var(--text-sm);color:var(--color-text-secondary)}.lesson__side{top:calc(var(--navbar-height) + var(--space-5));gap:var(--space-4);flex-direction:column;display:flex;position:sticky}@media (max-width:960px){.lesson__side{position:static}}.side-card{gap:var(--space-3);padding:var(--space-5);background:var(--color-bg-surface);border:1px solid var(--color-border);border-radius:var(--radius-lg);box-shadow:var(--shadow-sm);flex-direction:column;display:flex}.side-card>.text-secondary{font-size:var(--text-sm)}.side-card__row{gap:var(--space-2);flex-wrap:wrap;display:flex}.side-card__note{font-size:var(--text-sm);text-align:center}.side-card__done{align-items:center;gap:var(--space-3);font-size:var(--text-md);display:flex}.side-card__done span{background:var(--emerald);width:32px;height:32px;color:var(--white);font-weight:var(--weight-bold);border-radius:50%;flex:none;place-items:center;display:grid}.quiz__head{justify-content:space-between;align-items:baseline;gap:var(--space-2);display:flex}.quiz__head .text-muted,.quiz__prev{font-size:var(--text-sm)}.quiz__q{gap:var(--space-2);border:0;flex-direction:column;margin:0;padding:0;display:flex}.quiz__q legend{margin-bottom:var(--space-2);font-size:var(--text-md);font-weight:var(--weight-bold);line-height:var(--leading-snug);padding:0}.quiz__opt{align-items:center;gap:var(--space-3);min-height:48px;padding:var(--space-2) var(--space-3);text-align:left;border:1.5px solid var(--color-border-strong);border-radius:var(--radius-md);background:var(--color-bg-base);color:var(--color-text-primary);font:inherit;font-size:var(--text-sm);cursor:pointer;transition:border-color var(--duration-fast), background var(--duration-fast);display:flex}.quiz__opt:hover:not(:disabled){border-color:var(--color-text-primary)}.quiz__opt:disabled{cursor:default}.quiz__letter{border:1.5px solid var(--color-text-primary);width:28px;height:28px;font-size:var(--text-xs);font-weight:var(--weight-bold);border-radius:50%;flex:none;place-items:center;display:grid}.quiz__opt.is-right{border:2px solid var(--color-text-primary);background:var(--color-success-bg);color:var(--color-success-text);font-weight:var(--weight-semibold)}.quiz__opt.is-wrong{border:2px solid var(--color-text-primary);background:var(--color-danger-bg);color:var(--color-danger-text)}.quiz__explain{padding:var(--space-3);border-radius:var(--radius-md);background:var(--color-bg-overlay);font-size:var(--text-sm);color:var(--color-text-secondary)}.quiz__explain.is-right{background:var(--color-success-bg)}.quiz__explain b{color:var(--color-text-primary)}.quiz__score{font-size:var(--text-2xl);font-weight:var(--weight-bold)}.quiz .btn{align-self:flex-start}