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var(--color-border);border-radius:var(--radius-md);color:var(--color-text-secondary);font-weight:var(--font-semibold);cursor:pointer;transition:all var(--transition-fast)}.mark-complete:hover{border-color:var(--color-success);background:color-mix(in srgb,var(--color-success) 10%,var(--color-bg-secondary));color:var(--color-success)}.mark-complete--completed{background:var(--color-success);border-color:var(--color-success);color:#fff}.mark-complete--completed:hover{background:var(--color-success);border-color:var(--color-success);opacity:.9}.mark-complete__icon{font-size:var(--text-lg)}.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5rem;padding:.75rem 1.5rem;font-size:var(--text-base);font-weight:var(--font-semibold);text-decoration:none;border-radius:var(--radius-md);border:2px solid transparent;cursor:pointer;transition:all var(--transition-fast);white-space:nowrap;line-height:1}.btn:focus-visible{outline:2px solid 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.75rem;border-radius:var(--radius-full);font-size:var(--text-xs);font-weight:var(--font-semibold);text-transform:uppercase;letter-spacing:var(--tracking-wide);margin-block-end:var(--space-sm)}.lesson-card__title{font-size:var(--text-lg);font-weight:var(--font-bold);color:var(--color-text-secondary);margin-block-end:.5rem}.lesson-card__description{color:var(--color-text-tertiary);font-size:var(--text-sm);line-height:var(--leading-normal)}.lesson-card__meta{display:flex;gap:var(--space-md);align-items:center;margin-block-start:var(--space-md);font-size:var(--text-xs);color:var(--color-text-tertiary)}.lesson-card__status{position:absolute;top:var(--space-md);right:var(--space-md);color:var(--color-success);font-size:var(--text-lg)}.callout{display:flex;gap:var(--space-md);padding:var(--space-md);border-left:4px 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.callout__icon{color:var(--color-error)}.code-block{background:var(--color-code-bg);border:1px solid var(--color-border);border-radius:var(--radius-md);margin-block:var(--space-lg);overflow:hidden}.code-block__header{display:flex;justify-content:space-between;align-items:center;padding:var(--space-sm) var(--space-md);background:var(--color-bg-tertiary);border-bottom:1px solid var(--color-border)}.code-block__language{font-size:var(--text-xs);font-weight:var(--font-semibold);color:var(--color-text-tertiary);text-transform:uppercase;letter-spacing:var(--tracking-wide)}.code-block__copy{display:flex;align-items:center;gap:.5rem;padding:.25rem .75rem;background:transparent;border:1px solid var(--color-border);border-radius:var(--radius-sm);color:var(--color-text-tertiary);font-size:var(--text-xs);cursor:pointer;transition:all var(--transition-fast)}.code-block__copy:hover{background:var(--color-accent-teal);color:#fff;border-color:var(--color-accent-teal)}.code-block__copy--copied{background:var(--color-success);color:#fff;border-color:var(--color-success)}.badge{display:inline-block;padding:.25rem .75rem;font-size:var(--text-xs);font-weight:var(--font-semibold);border-radius:var(--radius-full);text-transform:uppercase;letter-spacing:var(--tracking-wide)}.badge--primary{background:var(--color-accent-primary);color:#fff}.badge--teal{background:var(--color-accent-teal);color:#fff}.badge--success{background:var(--color-success);color:#fff}.badge--neutral{background:var(--color-bg-tertiary);color:var(--color-text-secondary)}.progress{width:100%;height:.5rem;background:var(--color-bg-tertiary);border-radius:var(--radius-full);overflow:hidden}.progress__bar{height:100%;background:var(--color-accent-teal);border-radius:var(--radius-full);transition:width var(--transition-base)}.progress--large{height:1rem}.hero{text-align:center;padding-block:var(--space-3xl)}.hero__title{font-size:var(--text-4xl);font-weight:var(--font-bold);color:var(--color-text-secondary);margin-block-end:var(--space-md);line-height:var(--leading-tight)}.hero__description{font-size:var(--text-lg);color:var(--color-text-tertiary);max-width:60ch;margin-inline:auto;margin-block-end:var(--space-xl);line-height:var(--leading-relaxed)}.hero__actions{display:flex;gap:var(--space-md);justify-content:center;flex-wrap:wrap}.grid{display:grid;gap:var(--space-lg)}.grid--2{grid-template-columns:repeat(auto-fit,minmax(250px,1fr))}.grid--3{grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}.grid--4{grid-template-columns:repeat(auto-fit,minmax(180px,1fr))}.lesson-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:var(--space-lg);margin-block:var(--space-xl)}@media(max-width:640px){.lesson-grid{grid-template-columns:1fr}}.search-trigger{display:flex;align-items:center;gap:.4rem;padding:.4rem .75rem;background:var(--color-bg-tertiary);border:1px solid var(--color-border);border-radius:var(--radius-full);color:var(--color-text-tertiary);font-size:var(--text-sm);cursor:pointer;transition:all var(--transition-fast);white-space:nowrap}.search-trigger:hover{border-color:var(--color-accent-teal);color:var(--color-text-primary);background:var(--color-bg-accent)}.search-trigger:focus-visible{outline:2px solid var(--color-accent-teal);outline-offset:2px}.search-trigger__text{display:none}@media(min-width:640px){.search-trigger__text{display:inline}}.search-trigger__kbd{display:inline-flex;padding:.1rem .35rem;background:var(--color-bg-primary);border:1px solid var(--color-border);border-radius:var(--radius-sm);font-size:var(--text-xs);font-family:var(--font-mono);display:none}@media(min-width:768px){.search-trigger__kbd{display:inline-flex}}.search-overlay{position:fixed;inset:0;background:#0000008c;z-index:var(--z-modal-backdrop);display:flex;align-items:flex-start;justify-content:center;padding-block-start:10vh;padding-inline:var(--space-sm);opacity:0;visibility:hidden;transition:opacity var(--transition-fast),visibility var(--transition-fast)}.search-overlay.is-open{opacity:1;visibility:visible}.search-modal{background:var(--color-bg-primary);border:2px solid var(--color-border);border-radius:var(--radius-xl);width:100%;max-width:640px;box-shadow:var(--shadow-xl);overflow:hidden;transform:translateY(-16px) scale(.98);transition:transform var(--transition-fast)}.search-overlay.is-open .search-modal{transform:translateY(0) scale(1)}.search-input-wrapper{display:flex;align-items:center;gap:var(--space-sm);padding:var(--space-sm) var(--space-md);border-bottom:1px solid var(--color-border)}.search-icon{color:var(--color-text-tertiary);flex-shrink:0}.search-input{flex:1;border:none;outline:none;font-size:var(--text-lg);background:transparent;color:var(--color-text-primary);font-family:var(--font-sans)}.search-input::placeholder{color:var(--color-text-tertiary)}.search-input::-webkit-search-cancel-button{display:none}.search-clear{color:var(--color-text-tertiary);background:none;border:none;cursor:pointer;padding:.25rem;border-radius:var(--radius-sm);display:flex;align-items:center;opacity:0;visibility:hidden;transition:all var(--transition-fast)}.search-clear.is-visible{opacity:1;visibility:visible}.search-clear:hover{color:var(--color-text-primary);background:var(--color-bg-tertiary)}.search-results{max-height:420px;overflow-y:auto;scroll-padding-block:.5rem}.search-initial,.search-empty{padding:var(--space-xl) 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var(--color-border);border-radius:var(--radius-sm);font-family:var(--font-mono);font-size:var(--text-xs)}.code-wrapper{position:relative}.code-copy-btn{position:absolute;top:.5rem;right:.5rem;padding:.3rem .65rem;background:var(--color-bg-secondary);border:1px solid var(--color-border);border-radius:var(--radius-sm);font-size:var(--text-xs);font-family:var(--font-sans);color:var(--color-text-tertiary);cursor:pointer;opacity:0;transition:all var(--transition-fast);z-index:1}.code-wrapper:hover .code-copy-btn,.code-copy-btn:focus-visible{opacity:1}.code-copy-btn:hover{background:var(--color-accent-teal);color:#fff;border-color:var(--color-accent-teal)}.code-copy-btn.is-copied{background:var(--color-success);color:#fff;border-color:var(--color-success);opacity:1}.lesson-card.is-completed{border-color:var(--color-success)}.lesson-card.is-completed .lesson-card__badge{background:var(--color-success);color:#fff}.lesson-card__checkbox{position:absolute;top:var(--space-md);right:var(--space-md);width:1.25rem;height:1.25rem;border:2px solid var(--color-border);border-radius:var(--radius-sm);background:var(--color-bg-primary);display:flex;align-items:center;justify-content:center;cursor:pointer;padding:0;color:#fff;transition:border-color .15s,background .15s;flex-shrink:0}.lesson-card__checkbox:hover{border-color:var(--color-accent-primary)}.lesson-card__checkbox.is-checked{background:var(--color-success);border-color:var(--color-success)}.progress-action{padding-block:var(--space-xl);display:flex;justify-content:center}.mark-complete-btn{display:inline-flex;align-items:center;gap:.6rem;padding:.85rem 1.75rem;background:transparent;border:2px solid var(--color-success);border-radius:var(--radius-md);color:var(--color-success);font-size:var(--text-base);font-weight:var(--font-semibold);font-family:var(--font-sans);cursor:pointer;transition:all var(--transition-fast)}.mark-complete-btn:hover{background:var(--color-success);color:#fff;transform:translateY(-1px);box-shadow:var(--shadow-md)}.mark-complete-btn.is-completed{background:var(--color-success);color:#fff}.mark-complete-btn.is-completed:hover{background:transparent;color:var(--color-success);transform:none;box-shadow:none}.progress-summary{background:var(--color-bg-secondary);border:2px solid var(--color-border);border-radius:var(--radius-lg);padding:var(--space-lg)}.progress-summary__header{display:flex;justify-content:space-between;align-items:baseline;margin-block-end:var(--space-sm)}.progress-summary__label{font-size:var(--text-sm);font-weight:var(--font-semibold);color:var(--color-text-secondary)}.progress-summary__count{font-size:var(--text-sm);color:var(--color-text-tertiary)}.progress-summary__bar{width:100%;height:.5rem;background:var(--color-bg-tertiary);border-radius:var(--radius-full);overflow:hidden;margin-block-end:.4rem}.progress-summary__bar-fill{height:100%;background:var(--color-success);border-radius:var(--radius-full);transition:width .4s ease;width:0%}.progress-summary__pct{font-size:var(--text-xs);color:var(--color-text-tertiary);text-align:right;display:block}.reading-progress{position:fixed;top:0;left:0;width:100%;height:3px;z-index:calc(var(--z-fixed) + 10);pointer-events:none;background:transparent}.reading-progress__bar{height:100%;width:0%;background:linear-gradient(to right,var(--color-teal-bright),var(--color-accent-primary));transition:width 80ms linear}.back-to-top{position:fixed;bottom:2rem;right:2rem;width:2.75rem;height:2.75rem;background:var(--color-accent-teal);color:#fff;border:none;border-radius:var(--radius-full);cursor:pointer;display:flex;align-items:center;justify-content:center;z-index:var(--z-fixed);opacity:0;visibility:hidden;transform:translateY(10px);transition:opacity var(--transition-fast),visibility var(--transition-fast),transform var(--transition-fast),background var(--transition-fast);box-shadow:var(--shadow-lg)}.back-to-top.is-visible{opacity:1;visibility:visible;transform:translateY(0)}.back-to-top:hover{background:var(--color-teal-dark);transform:translateY(-2px);box-shadow:var(--shadow-xl)}.back-to-top:focus-visible{outline:2px solid var(--color-accent-teal);outline-offset:3px}.lesson-with-toc{display:grid;grid-template-columns:1fr;gap:var(--space-xl);align-items:start}@media(min-width:1100px){.lesson-with-toc{grid-template-columns:1fr var(--toc-width)}}.lesson-toc{display:none}@media(min-width:1100px){.lesson-toc{display:block;position:sticky;top:calc(var(--header-height) + var(--space-md));max-height:calc(100vh - var(--header-height) - 2rem);overflow-y:auto;scrollbar-width:thin}}.toc__link--h3{padding-inline-start:1.25rem;font-size:var(--text-xs)}@media print{.site-header,.mobile-menu,.mobile-menu__backdrop,.reading-progress,.back-to-top,.lesson-toc,.progress-action,.lesson-nav,.breadcrumbs,.lesson-progress,.skip-link,footer{display:none!important}body{font-size:11pt;color:#000;background:#fff}.site-layout{display:block}main{padding:0}.lesson-with-toc{display:block}pre,code{background:#f5f5f5!important;color:#000!important;border:1px solid #ccc!important;font-size:9pt;page-break-inside:avoid;white-space:pre-wrap;word-break:break-all}h1,h2{page-break-after:avoid}a[href]:after{content:" (" attr(href) ")";font-size:8pt;color:#555}a[href^="#"]:after,a[href^="javascript:"]:after{content:""}}