.sy-learn-bar{position:-webkit-sticky;position:sticky;inset-block-start:0;z-index:60;background:var(--sy-brand-gradient);color:var(--sy-on-brand);--wm-color:var(--sy-on-brand);--wm-opacity:0.07;--wm-size:220px;--wm-x:2%;--wm-y-end:-100px}.sy-learn-bar :focus-visible{outline-color:var(--sy-brand-bright)}.sy-learn-home{display:grid;place-items:center;flex:none;inline-size:40px;block-size:40px;border-radius:var(--sy-r-2);background:color-mix(in srgb,var(--sy-on-brand) 12%,transparent);border:1px solid color-mix(in srgb,var(--sy-on-brand) 16%,transparent);--sy-brand-mark:var(--sy-on-brand);transition:background .16s var(--sy-ease)}.sy-learn-home:hover{background:color-mix(in srgb,var(--sy-on-brand) 20%,transparent)}.sy-learn-home svg{block-size:15px;inline-size:auto}.sy-learn-back{display:inline-flex;align-items:center;gap:5px;min-block-size:24px;-webkit-margin-after:2px;margin-block-end:2px;font-size:var(--sy-text-xs);font-weight:600;color:var(--sy-on-brand-2)}.sy-learn-back:hover{color:var(--sy-on-brand)}.sy-chapter-btn{transition:background .14s var(--sy-ease)}.sy-chapter-btn:hover{background:var(--sy-surface-2)}.sy-section-row{transition:background .14s var(--sy-ease)}.sy-section-row:hover{background:var(--sy-surface-3)}@media (max-width:560px){.sy-hide-narrow{display:none!important}}.sy-lesson-bar{position:-webkit-sticky;position:sticky;inset-block-start:0;z-index:50;background:var(--sy-brand-surface);color:var(--sy-on-brand);-webkit-border-after:1px solid color-mix(in srgb,var(--sy-on-brand) 8%,transparent);border-block-end:1px solid color-mix(in srgb,var(--sy-on-brand) 8%,transparent)}.sy-lesson-bar-row{max-inline-size:1100px;margin-inline:auto;display:flex;align-items:center;gap:10px;flex-wrap:wrap;min-inline-size:0;padding:10px clamp(16px,3vw,24px)}.sy-lesson-bar a{display:inline-flex;align-items:center;gap:6px;min-block-size:32px;color:var(--sy-on-brand-3);font-size:var(--sy-text-xs);flex:none}.sy-lesson-bar a:hover{color:var(--sy-on-brand)}.sy-lesson-bar :focus-visible{outline-color:var(--sy-brand-bright)}@media (max-width:560px){.sy-lesson-chapter{display:none!important}.sy-lesson-bar-row{flex-wrap:nowrap}}.sy-lesson-bar h1{flex:1 1;min-inline-size:0;margin:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-size:var(--sy-text-sm);font-weight:700;color:var(--sy-on-brand)}.sy-lesson-panel{padding:20px 22px;border:1px solid var(--sy-line);border-radius:var(--sy-r-4);background:var(--sy-surface)}.sy-lesson-panel-title{display:flex;align-items:center;gap:8px;margin:0 0 14px;font-size:var(--sy-text-md);font-weight:800;color:var(--sy-fg)}.sy-lesson-panel-title svg{color:var(--sy-brand)}.sy-lesson-objective{display:grid;grid-gap:4px;gap:4px;padding:14px 18px;-webkit-margin-after:16px;margin-block-end:16px;border-radius:var(--sy-r-3);background:var(--sy-brand-subtle);border:1px solid var(--sy-brand-line);-webkit-border-start:4px solid var(--sy-brand);border-inline-start:4px solid var(--sy-brand)}.sy-lesson-objective span{display:flex;align-items:center;gap:6px;font-size:var(--sy-text-xs);font-weight:800;color:var(--sy-brand)}.sy-lesson-objective p{margin:0;font-size:var(--sy-text-sm);color:var(--sy-fg);line-height:1.9}.sy-lesson-tabs{inline-size:100%;-webkit-margin-after:16px;margin-block-end:16px;overflow-x:auto;scrollbar-width:none}.sy-lesson-tabs::-webkit-scrollbar{display:none}.sy-lesson-tabs>button{flex:1 0 auto}.sy-file-row{display:flex;align-items:center;gap:12px;padding:12px 14px;border-radius:var(--sy-r-3);background:var(--sy-surface-2);border:1px solid var(--sy-line)}.sy-file-row[data-viewed=true]{border-color:var(--sy-ok-line)}.sy-file-ext{display:grid;place-items:center;flex:none;inline-size:42px;block-size:42px;background:var(--sy-brand-subtle);color:var(--sy-brand);font-size:var(--sy-text-2xs);font-weight:800;letter-spacing:.04em;direction:ltr}.sy-file-ext,.sy-ref{border-radius:var(--sy-r-2)}.sy-ref{padding:12px 14px;background:var(--sy-surface-2);-webkit-border-start:3px solid var(--sy-brand);border-inline-start:3px solid var(--sy-brand)}.sy-lesson-side{position:-webkit-sticky;position:sticky;inset-block-start:70px;display:grid;grid-gap:14px;gap:14px}.sy-check-row{display:flex;align-items:center;gap:8px;font-size:var(--sy-text-sm)}.sy-check-row+.sy-check-row{-webkit-margin-before:10px;margin-block-start:10px}.sy-option{display:flex;gap:12px;align-items:center;inline-size:100%;padding:12px 14px;border:1.5px solid var(--sy-line);border-radius:var(--sy-r-3);background:var(--sy-surface);color:var(--sy-fg);font:inherit;text-align:start;cursor:pointer;transition:border-color .15s var(--sy-ease),background .15s var(--sy-ease)}.sy-option:hover:not(:disabled){border-color:var(--sy-brand-line);background:var(--sy-surface-2)}.sy-option[aria-pressed=true]{border-color:var(--sy-brand);background:var(--sy-brand-subtle)}.sy-option[data-result=correct]{border-color:var(--sy-ok);background:var(--sy-ok-subtle)}.sy-option[data-result=wrong]{border-color:var(--sy-danger);background:var(--sy-danger-subtle)}.sy-option:disabled{cursor:default}.sy-option-key{display:grid;place-items:center;flex:none;inline-size:30px;block-size:30px;border-radius:50%;background:var(--sy-surface-3);color:var(--sy-fg-3);font-size:var(--sy-text-sm);font-weight:800}.sy-option[aria-pressed=true] .sy-option-key{background:var(--sy-brand-fill);color:var(--sy-on-brand-fill)}.sy-option-text{flex:1 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