:root { --ink: #17221b; --paper: #f4f0e6; --cream: #fffdf7; --moss: #315c45; --lime: #d8e66a; --rust: #b95733; --rule: #c9c2b2; --dark-surface: #17221b; --glow: #fff9dc; --hover: #fff8e8; --accent-wash: #fff8e8; --code-inline: #e5e1d6; --takeaway: #eef1d1; --muted: #666; --sidebar-ink: #f7f2e7; --on-dark: #f7f2e7; font-family: Georgia, "Times New Roman", serif; color: var(--ink); background: var(--paper); color-scheme: light; }
:root[data-theme="dark"] { --ink: #edf2e8; --paper: #111812; --cream: #1b261e; --moss: #78b68c; --lime: #cadb58; --rust: #eb8c67; --rule: #3b4b3e; --dark-surface: #09100b; --glow: #263629; --hover: #28362b; --accent-wash: #2a352b; --code-inline: #2a352c; --takeaway: #30402c; --muted: #a9b4aa; --sidebar-ink: #f2f5ed; --on-dark: #f2f5ed; color-scheme: dark; }
html[lang="ja"] { font-family: "Hiragino Kaku Gothic ProN", "Yu Gothic", "Noto Sans JP", sans-serif; }
html[lang="ja"] h1, html[lang="ja"] h2, html[lang="ja"] h4 { letter-spacing: 0; }
html[lang="ja"] h1 { line-height: 1.15; }
html[lang="ja"] h2 { line-height: 1.25; }
html[lang="ja"] .chapter-body { line-height: 1.9; }
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: radial-gradient(circle at 80% 0, var(--glow) 0, transparent 30rem), var(--paper); }
a { color: inherit; text-underline-offset: .2em; }
.sidebar { position: fixed; inset: 0 auto 0 0; width: 19rem; display: flex; flex-direction: column; padding: 2rem 1.35rem; color: var(--sidebar-ink); background: var(--dark-surface); border-right: .45rem solid var(--lime); overflow-y: auto; }
.brand { display: grid; gap: .45rem; text-decoration: none; padding: 0 .55rem 1.75rem; border-bottom: 1px solid #ffffff2d; }
.brand span, .eyebrow, .source-card span, .reconstruction-label, .chapter-time, .example-label { font: 700 .72rem/1.2 Arial, sans-serif; text-transform: uppercase; letter-spacing: .14em; }
.brand strong { font-size: 1.2rem; line-height: 1.15; }
nav ol { list-style: none; padding: 1rem 0; margin: 0; }
nav a { display: grid; grid-template-columns: 2rem 1fr auto; gap: .45rem; align-items: baseline; padding: .72rem .55rem; border-radius: .3rem; text-decoration: none; font-size: .9rem; }
nav a:hover, nav a.active { background: #ffffff13; color: var(--lime); }
.theme-toggle { align-self: start; margin: 1rem .55rem; padding: .55rem .7rem; color: inherit; background: transparent; border: 1px solid currentColor; border-radius: .2rem; cursor: pointer; font: 700 .7rem Arial, sans-serif; letter-spacing: .04em; }
.theme-toggle:hover, .theme-toggle:focus-visible { color: var(--lime); }
.library-link { align-self: start; margin: 0 .55rem 1.25rem; color: var(--lime); font: 700 .72rem Arial, sans-serif; text-underline-offset: .2em; }
nav a span, nav a small { font: 700 .68rem Arial, sans-serif; opacity: .7; }
.source-card { display: grid; gap: .35rem; margin-top: auto; padding: 1rem; color: var(--ink); background: var(--lime); text-decoration: none; transform: rotate(-1deg); box-shadow: .25rem .3rem 0 #0005; }
.source-card small { font: .72rem Arial, sans-serif; }
main { min-width: 0; margin-left: 19rem; }
.hero { min-height: 68vh; display: flex; flex-direction: column; justify-content: end; padding: clamp(3rem, 8vw, 8rem) clamp(1.5rem, 7vw, 7rem) 4rem; border-bottom: 1px solid var(--rule); }
.eyebrow { color: var(--rust); }
h1 { max-width: 15ch; margin: .5rem 0 1.5rem; font-size: clamp(3rem, 7vw, 7rem); font-weight: 400; line-height: .9; letter-spacing: -.055em; }
.summary { max-width: 48rem; font-size: 1.2rem; line-height: 1.65; }
.summary p { margin: 0 0 1rem; }
.hero > a { align-self: start; margin-top: 1rem; font: 700 .8rem Arial, sans-serif; color: var(--moss); }
.language-switch { align-self: start; margin: .8rem 0 0; font: 700 .8rem/1.4 Arial, sans-serif; color: var(--rust); }
.language-switch a, .edition-link { text-underline-offset: .2em; }
.chapter-index, .chapter-page { max-width: 78rem; padding: clamp(4rem, 8vw, 7rem) clamp(1.25rem, 5vw, 5rem); }
.chapter-index > h2 { max-width: 12ch; margin-bottom: 2rem; }
.chapter-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; padding: 0; list-style: none; }
.chapter-list a { display: grid; grid-template-columns: auto 1fr; gap: .45rem 1rem; height: 100%; padding: 1.5rem; background: var(--cream); border: 1px solid var(--rule); border-top: .35rem solid var(--rust); text-decoration: none; }
.chapter-list a:hover { background: var(--hover); transform: translateY(-.15rem); }
.chapter-list span { grid-row: 1 / 3; display: grid; place-items: center; width: 3rem; aspect-ratio: 1; color: var(--on-dark); background: var(--rust); border-radius: 50%; font: 700 .8rem Arial, sans-serif; }
.chapter-list strong { align-self: end; font-size: 1.25rem; font-weight: 400; }
.chapter-list small { color: var(--moss); font: 700 .68rem Arial, sans-serif; }
.chapter-page { min-height: 100vh; }
.chapter { scroll-margin-top: 2rem; padding: 6rem 0; border-bottom: 1px solid var(--rule); }
.chapter-header { display: grid; grid-template-columns: auto 1fr auto; gap: 1.2rem; align-items: start; margin-bottom: 3rem; }
.chapter-number { display: grid; place-items: center; width: 3.4rem; aspect-ratio: 1; color: var(--on-dark); background: var(--rust); border-radius: 50%; font: 700 1rem Arial, sans-serif; }
.chapter-time { margin: 0 0 .35rem; color: var(--moss); }
h2 { margin: 0; font-size: clamp(2rem, 4vw, 4rem); font-weight: 400; line-height: 1; letter-spacing: -.035em; }
h3 { margin: 0 0 1rem; font: 700 .76rem Arial, sans-serif; text-transform: uppercase; letter-spacing: .12em; }
.watch-link { padding: .65rem .8rem; border: 1px solid var(--ink); font: 700 .72rem Arial, sans-serif; text-decoration: none; }
.chapter-body { max-width: 52rem; font-size: 1.12rem; line-height: 1.72; }
.chapter-body h2 { margin: 3.5rem 0 1rem; font-size: clamp(1.8rem, 3vw, 2.8rem); }
.chapter-body h3 { margin: 2.5rem 0 .8rem; color: var(--moss); }
.chapter-body h4 { margin: 2rem 0 .6rem; font-size: 1.2rem; }
.chapter-body p, .chapter-body ul, .chapter-body ol, .chapter-body pre, .chapter-body blockquote, .chapter-body table { margin: 0 0 1.25rem; }
.chapter-body li + li { margin-top: .55rem; }
.chapter-body blockquote { margin-left: 0; padding: 1rem 1.3rem; background: var(--accent-wash); border-left: .3rem solid var(--rust); }
.chapter-body code { padding: .12rem .3rem; font-size: .9em; background: var(--code-inline); border-radius: .2rem; }
.chapter-body pre { overflow-x: auto; padding: 1rem; color: var(--on-dark); background: var(--dark-surface); }
.chapter-body pre code { padding: 0; color: inherit; background: transparent; }
.chapter-body table { width: 100%; border-collapse: collapse; background: var(--cream); }
.chapter-body th, .chapter-body td { padding: .7rem; border: 1px solid var(--rule); text-align: left; }
.chapter-body img { max-width: 100%; height: auto; }
.idea, .explanation { margin: 1rem 0; padding: 1.5rem; }
.idea { max-width: 46rem; margin-left: 8%; border-left: .3rem solid var(--rust); background: var(--accent-wash); font-size: 1.15rem; }
.explanation { max-width: 58rem; padding: clamp(1.5rem, 4vw, 3rem); color: var(--on-dark); background: var(--moss); font-size: 1.15rem; line-height: 1.7; box-shadow: .6rem .6rem 0 var(--lime); }
.explanation h4 { margin: 2rem 0 .5rem; font-size: 1.4rem; font-weight: 400; line-height: 1.2; }
.explanation > h3 + h4 { margin-top: 0; }
.idea > :last-child, .explanation > :last-child { margin-bottom: 0; }
.examples { margin: 3.5rem 0; }
.example-card { display: grid; grid-template-columns: minmax(12rem, .7fr) minmax(16rem, 1.3fr); gap: 1.5rem 2rem; margin: 1rem 0; padding: 1.5rem; background: var(--cream); border: 1px solid var(--rule); border-top: .35rem solid var(--rust); }
.example-card header { align-self: start; }
.example-card h4 { margin: .7rem 0; font-size: 1.45rem; font-weight: 400; line-height: 1.1; }
.example-label { display: inline-block; padding: .35rem .5rem; color: var(--on-dark); background: var(--rust); }
.example-label.source { color: var(--ink); background: var(--lime); }
.example-card ol { grid-column: 2; margin: 0; padding-left: 1.4rem; line-height: 1.55; }
.example-card li + li { margin-top: .65rem; }
.example-card li p, .example-scenario > :first-child, .example-takeaway > :first-child { margin-top: 0; }
.example-card li p, .example-scenario > :last-child, .example-takeaway > :last-child { margin-bottom: 0; }
.example-takeaway { grid-column: 2; padding: 1rem; background: var(--takeaway); line-height: 1.5; }
.example-takeaway strong { display: block; margin-bottom: .4rem; font: 700 .72rem Arial, sans-serif; text-transform: uppercase; letter-spacing: .12em; }
.study-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1px; margin: 3.5rem 0; background: var(--rule); border: 1px solid var(--rule); }
.study-grid section { padding: 1.4rem; background: var(--cream); }
.study-grid ul { padding-left: 1.1rem; line-height: 1.5; }
.study-grid li + li { margin-top: .7rem; }
.study-grid li p { margin: 0; }
.empty-note { color: #67675e; font-style: italic; }
.visuals, .diagrams { margin-top: 4rem; }
figure { margin: 1.5rem 0; background: var(--cream); border: 1px solid var(--rule); }
figure img { display: block; width: 100%; max-height: 40rem; object-fit: contain; background: #dedbd2; }
.image-zoom-trigger { position: relative; display: block; width: 100%; padding: 0; color: inherit; background: none; border: 0; cursor: zoom-in; }
.image-zoom-trigger span { position: absolute; right: .75rem; bottom: .75rem; padding: .45rem .6rem; color: var(--on-dark); background: #17221bd9; font: 700 .68rem Arial, sans-serif; text-transform: uppercase; letter-spacing: .08em; opacity: 0; transition: opacity .15s ease; }
.image-zoom-trigger:hover span, .image-zoom-trigger:focus-visible span { opacity: 1; }
.image-zoom-trigger:focus-visible { outline: .25rem solid var(--rust); outline-offset: .2rem; }
.image-lightbox { width: 96vw; max-width: none; height: 94vh; max-height: none; padding: 0; overflow: hidden; color: var(--on-dark); background: #101712; border: 1px solid #ffffff38; }
.image-lightbox[open] { display: flex; flex-direction: column; }
.image-lightbox::backdrop { background: #101712e8; }
.image-lightbox-toolbar { display: flex; gap: .5rem; align-items: center; padding: .65rem; color: var(--on-dark); background: var(--dark-surface); }
.image-lightbox-toolbar button { padding: .5rem .7rem; color: var(--on-dark); background: #ffffff12; border: 1px solid #ffffff70; cursor: pointer; font: 700 .72rem Arial, sans-serif; }
.image-lightbox-toolbar button:not(:disabled):hover, .image-lightbox-toolbar button:not(:disabled):focus-visible { color: var(--dark-surface); background: var(--lime); border-color: var(--lime); }
.image-lightbox-toolbar button:disabled { cursor: not-allowed; opacity: .35; }
.image-lightbox-toolbar output { min-width: 3.5rem; text-align: center; font: 700 .72rem Arial, sans-serif; }
.image-lightbox-toolbar span { margin-left: .5rem; color: #ffffffa8; font: .72rem Arial, sans-serif; }
.image-lightbox-close { margin-left: auto; text-transform: uppercase; letter-spacing: .08em; }
.image-lightbox-viewport { flex: 1; min-height: 0; overflow: auto; overscroll-behavior: contain; background: #252a27; touch-action: none; }
.image-lightbox-viewport.pan-ready { cursor: grab; }
.image-lightbox-viewport.dragging { cursor: grabbing; }
.image-lightbox-viewport:focus-visible { outline: .2rem solid var(--lime); outline-offset: -.2rem; }
.image-lightbox-canvas { position: relative; margin: auto; }
.image-lightbox-canvas img { display: block; width: 100%; height: 100%; background: #dedbd2; box-shadow: 0 1rem 4rem #0009; user-select: none; }
figcaption { display: grid; gap: .55rem; padding: 1rem 1.2rem; }
figcaption span p { margin: 0; }
.timestamp, .diagram-source { justify-self: start; font: 700 .72rem Arial, sans-serif; color: var(--rust); }
.diagram-card { padding: 1rem; border-top: .4rem solid var(--lime); }
.reconstruction-label { justify-self: start; padding: .35rem .5rem; color: var(--ink); background: var(--lime); }
.mermaid { overflow-x: auto; padding: 1rem; text-align: center; }
.diagram-source { display: inline-block; margin: 0 1.2rem 1rem; }
.chapter-pager { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; margin-top: 5rem; }
.chapter-pager a { display: grid; gap: .35rem; padding: 1rem; background: var(--cream); border: 1px solid var(--rule); text-decoration: none; }
.chapter-pager a[rel="next"] { text-align: right; }
.chapter-pager span { color: var(--rust); font: 700 .68rem Arial, sans-serif; text-transform: uppercase; letter-spacing: .12em; }
footer { padding: 3rem clamp(1.25rem, 5vw, 5rem); font: .75rem/1.5 Arial, sans-serif; color: var(--muted); }

.catalog-body { min-height: 100vh; }
.catalog-topbar { display: flex; justify-content: space-between; align-items: center; padding: 1.25rem clamp(1.25rem, 5vw, 5rem); border-bottom: 1px solid var(--rule); }
.catalog-brand { display: grid; gap: .25rem; color: var(--ink); text-decoration: none; }
.catalog-brand span { color: var(--rust); font: 700 .72rem Arial, sans-serif; text-transform: uppercase; letter-spacing: .14em; }
.catalog-brand strong { font-size: 1.3rem; font-weight: 400; }
.catalog-topbar .theme-toggle { margin: 0; }
.catalog-main { max-width: 94rem; margin: 0 auto; padding: 0 clamp(1.25rem, 5vw, 5rem) 5rem; }
.catalog-hero { display: grid; align-content: end; min-height: 58vh; max-width: 70rem; padding: clamp(4rem, 9vw, 9rem) 0 4rem; border-bottom: 1px solid var(--rule); }
.catalog-hero h1 { max-width: 11ch; margin: .5rem 0 1.2rem; }
.catalog-hero > p:not(.eyebrow) { max-width: 38rem; margin: 0; font-size: 1.25rem; line-height: 1.5; }
.catalog-count { margin-top: 2rem; color: var(--moss); font: 700 .75rem Arial, sans-serif; text-transform: uppercase; letter-spacing: .1em; }
.catalog-section-heading { display: flex; justify-content: space-between; align-items: end; gap: 2rem; padding: 4rem 0 2rem; }
.catalog-section-heading h2 { font-size: clamp(2rem, 5vw, 4rem); }
.lesson-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; margin: 0; padding: 0; list-style: none; }
.lesson-card > a { position: relative; display: grid; grid-template-columns: auto 1fr auto; gap: 1rem; min-height: 15rem; padding: 1.5rem; color: var(--ink); background: var(--cream); border: 1px solid var(--rule); border-top: .35rem solid var(--rust); text-decoration: none; transition: transform .15s ease, background .15s ease; }
.lesson-card > a:hover, .lesson-card > a:focus-visible { background: var(--hover); transform: translateY(-.15rem); }
.lesson-card-number { display: grid; place-items: center; width: 3rem; height: 3rem; color: var(--on-dark); background: var(--rust); border-radius: 50%; font: 700 .8rem Arial, sans-serif; }
.lesson-card .eyebrow { margin: .15rem 0 .6rem; }
.lesson-card h2 { max-width: 17ch; margin: 0 0 1rem; font-size: clamp(1.4rem, 2.5vw, 2.25rem); }
.lesson-card p:not(.eyebrow) { max-width: 38rem; margin: 0 0 1rem; color: var(--muted); font-size: .98rem; line-height: 1.5; }
.lesson-card small { color: var(--moss); font: 700 .68rem Arial, sans-serif; }
.lesson-card-arrow { align-self: end; color: var(--rust); font: 700 1.2rem Arial, sans-serif; }
.lesson-card-languages { display: flex; gap: .55rem; padding: .65rem .8rem; background: var(--dark-surface); }
.lesson-card-languages a { color: var(--sidebar-ink); font: 700 .72rem Arial, sans-serif; text-underline-offset: .2em; }
.lesson-card-languages a:hover, .lesson-card-languages a:focus-visible { color: var(--lime); }
.empty-note { padding: 2rem; color: var(--muted); background: var(--cream); border: 1px solid var(--rule); }
.chapter-body, .chapter-list strong, .lesson-card h2 { overflow-wrap: anywhere; }
.navigation-toggle { display: none; }
.mobile-navigation { display: none; }
.mobile-navigation-links { display: flex; gap: .5rem; }
.mobile-nav-link { color: var(--sidebar-ink); background: #ffffff0d; border: 1px solid #ffffff36; text-decoration: none; }
.mobile-chapter-menu summary { cursor: pointer; list-style: none; }
.mobile-chapter-menu summary::-webkit-details-marker { display: none; }
.mobile-chapter-menu summary::after { content: "+"; float: right; color: var(--lime); font: 700 1rem Arial, sans-serif; }
.mobile-chapter-menu[open] summary::after { content: "-"; }
@media (max-width: 800px) {
  .sidebar { position: sticky; z-index: 4; top: 0; width: auto; min-width: 0; height: auto; padding: .75rem 1rem .8rem; border-right: 0; border-bottom: .3rem solid var(--lime); box-shadow: 0 .35rem 1rem #0003; }
  .brand { min-width: 0; padding: 0 9.5rem 0 0; border: 0; }
  .brand span, .sidebar > .chapter-navigation, .source-card, .library-link { display: none; }
  .brand strong { display: block; max-width: 100%; font-size: 1.05rem; line-height: 1.15; overflow-wrap: anywhere; }
  .sidebar .theme-toggle { position: absolute; top: .6rem; right: 1rem; width: 5.5rem; min-height: 2.75rem; margin: 0; padding: .55rem .65rem; }
  .navigation-toggle { position: absolute; top: .6rem; right: 6.75rem; display: grid; place-items: center; width: 2.75rem; min-height: 2.75rem; margin: 0; padding: .55rem; color: inherit; background: transparent; border: 1px solid currentColor; border-radius: .2rem; cursor: pointer; font: 700 1rem/1 Arial, sans-serif; }
  .navigation-toggle:hover, .navigation-toggle:focus-visible { color: var(--lime); }
  .sidebar.navigation-collapsed { padding-bottom: .65rem; }
  .sidebar.navigation-collapsed .brand { padding-bottom: 0; }
  .sidebar.navigation-collapsed .brand strong { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .sidebar.navigation-collapsed .mobile-navigation { display: none; }
  .mobile-navigation { display: grid; gap: .55rem; margin-top: .75rem; }
  .mobile-navigation-links { min-width: 0; margin: 0 -.1rem; padding: .1rem .1rem .15rem; overflow-x: auto; scrollbar-width: none; }
  .mobile-navigation-links::-webkit-scrollbar { display: none; }
  .mobile-nav-link { display: inline-flex; flex: 0 0 auto; align-items: center; min-height: 2.75rem; padding: .55rem .7rem; border-radius: .2rem; font: 700 .7rem/1.2 Arial, sans-serif; white-space: nowrap; }
  .mobile-nav-link:hover, .mobile-nav-link:focus-visible { color: var(--lime); background: #ffffff18; }
  .mobile-chapter-menu summary { min-height: 2.75rem; padding: .7rem; color: var(--sidebar-ink); border: 1px solid #ffffff36; font: 700 .7rem/1.2 Arial, sans-serif; text-transform: uppercase; letter-spacing: .08em; }
  .mobile-chapter-menu nav { max-height: min(55vh, 28rem); overflow-y: auto; padding-top: .25rem; }
  .mobile-chapter-menu nav ol { padding: 0; }
  .mobile-chapter-menu nav a { padding: .65rem .45rem; font-size: .84rem; }
  main { margin-left: 0; }
  .hero { min-height: 55vh; padding: clamp(3.5rem, 14vw, 6rem) 1.25rem 3rem; }
  h1 { font-size: clamp(2.7rem, 12vw, 4.5rem); }
  .summary { font-size: 1.08rem; line-height: 1.6; }
  .chapter-index, .chapter-page { padding: 3.5rem 1.1rem; }
  .chapter-index > h2 { scroll-margin-top: 8rem; }
  .chapter-list, .lesson-list { grid-template-columns: 1fr; }
  .chapter-header { grid-template-columns: auto minmax(0, 1fr); gap: .8rem; }
  .chapter-header h1 { margin: .35rem 0 0; font-size: clamp(2rem, 9vw, 3.5rem); }
  .chapter-number { width: 2.8rem; }
  .watch-link { grid-column: 2; justify-self: start; display: inline-flex; align-items: center; min-height: 2.75rem; }
  .chapter-body { font-size: 1.05rem; line-height: 1.7; }
  .chapter-body table { display: block; max-width: 100%; overflow-x: auto; }
  .chapter-body th, .chapter-body td { padding: .6rem; }
  .example-card { grid-template-columns: 1fr; }
  .example-card ol, .example-takeaway { grid-column: 1; }
  .study-grid { grid-template-columns: 1fr; }
  .idea { margin-left: 0; }
  .chapter-pager { grid-template-columns: 1fr; gap: .75rem; margin-top: 3.5rem; }
  .chapter-pager a[rel="next"] { text-align: left; }
  .image-lightbox { width: 100vw; height: 100vh; }
  .image-lightbox-toolbar { flex-wrap: wrap; }
  .image-lightbox-toolbar button { min-height: 2.75rem; }
  .image-lightbox-toolbar span { display: none; }
  .catalog-topbar { align-items: flex-start; gap: .75rem; padding: .9rem 1rem; }
  .catalog-topbar .theme-toggle { min-height: 2.75rem; padding: .55rem .65rem; }
  .catalog-main { padding: 0 1rem 3rem; }
  .catalog-hero { min-height: 48vh; padding: clamp(3.5rem, 16vw, 6rem) 0 3rem; }
  .catalog-hero h1 { font-size: clamp(2.7rem, 13vw, 4rem); }
  .catalog-hero > p:not(.eyebrow) { font-size: 1.1rem; }
  .catalog-section-heading { display: block; }
  .catalog-section-heading h2 { margin-top: .75rem; }
  .lesson-card > a { grid-template-columns: auto minmax(0, 1fr) auto; gap: .75rem; min-height: 0; padding: 1.1rem; }
  .lesson-card-number { width: 2.5rem; height: 2.5rem; }
  .lesson-card h2 { max-width: none; font-size: clamp(1.35rem, 6vw, 1.8rem); }
  .lesson-card p:not(.eyebrow) { font-size: .95rem; }
  footer { padding: 2rem 1rem; }
}
@media print { .sidebar { display: none; } main { margin: 0; } .chapter { break-before: page; } .hero { min-height: auto; } }