/* =================================================================
   早稲田の公民 実況中継 — Web参考書プロトタイプ
   深緑 × ゴールド × アイボリー
   v1 (prototype: top + list + 2 lectures)
   ================================================================= */

/* -----------------------------------------------------------------
   1. Design tokens
----------------------------------------------------------------- */
:root {
  /* Color */
  --c-pine:        #1F3D2E;
  --c-pine-dark:   #142A1F;
  --c-sage:        #E8EFEA;
  --c-sage-deep:   #C4D5C9;
  --c-gold:        #C9A961;
  --c-gold-dark:   #A78940;
  --c-champagne:   #F4ECD7;
  --c-ivory:       #FBF8F1;
  --c-paper:       #FFFFFF;
  --c-sumi:        #1B1B1B;
  --c-charcoal:    #4A4A4A;
  --c-mute:        #7A7A6E;
  --c-line:        #D9D2BE;
  --c-crimson:     #9A2B2B;
  --c-indigo:      #2E4F6E;

  /* Confidence colors */
  --c-high:        #1F3D2E;
  --c-medium:      #A78940;
  --c-low:         #9A2B2B;
  --c-warn:        #B7762A;

  /* Type */
  --ff-mincho: "Noto Serif JP", "Hiragino Mincho ProN", "Yu Mincho", "MS Mincho", serif;
  --ff-gothic: "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", sans-serif;
  --ff-serif:  "Crimson Pro", "Cormorant Garamond", "Times New Roman", serif;

  /* Layout */
  --content-w: 760px;
  --content-w-wide: 1080px;
  --gutter: 24px;

  /* Misc */
  --r-sm: 2px;
  --r-md: 4px;
  --r-lg: 8px;
  --sh-card: 0 1px 0 rgba(31,61,46,.06), 0 8px 24px -16px rgba(31,61,46,.18);
}

/* -----------------------------------------------------------------
   2. Reset & base
----------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { font-size: 16px; -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--c-ivory);
  color: var(--c-sumi);
  font-family: var(--ff-gothic);
  font-size: 1rem;
  line-height: 1.85;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; }
a { color: var(--c-pine); text-decoration: underline; text-underline-offset: 3px; text-decoration-thickness: 1px; }
a:hover { color: var(--c-gold-dark); }
a:focus-visible { outline: 2px solid var(--c-gold); outline-offset: 2px; }
:where(p, ul, ol, blockquote, table) { margin: 0 0 1em; }
hr { border: none; border-top: 1px solid var(--c-line); margin: 2em 0; }

/* -----------------------------------------------------------------
   3. Header / Nav
----------------------------------------------------------------- */
.site-header {
  background: var(--c-pine);
  color: var(--c-ivory);
  border-bottom: 2px solid var(--c-gold);
  position: sticky; top: 0; z-index: 50;
}
.site-header__inner {
  max-width: var(--content-w-wide);
  margin: 0 auto;
  padding: 12px var(--gutter);
  display: flex; align-items: center; gap: 18px; flex-wrap: wrap;
}
.site-title {
  font-family: var(--ff-mincho);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  margin: 0;
}
.site-title a { color: inherit; text-decoration: none; }
.site-title small {
  display: block;
  font-family: var(--ff-serif);
  font-style: italic;
  letter-spacing: 0.18em;
  font-size: 0.6rem;
  color: var(--c-champagne);
  margin-top: 2px;
}

.site-nav { margin-left: auto; }
.site-nav__list {
  list-style: none; margin: 0; padding: 0;
  display: flex; gap: 18px; flex-wrap: wrap;
}
.site-nav__list a {
  color: var(--c-ivory);
  text-decoration: none;
  font-family: var(--ff-mincho);
  font-size: 0.92rem;
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  letter-spacing: 0.04em;
}
.site-nav__list a:hover,
.site-nav__list a[aria-current="page"] {
  border-bottom-color: var(--c-gold);
  color: var(--c-gold);
}

.nav-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--c-champagne);
  color: var(--c-ivory);
  padding: 6px 10px;
  border-radius: var(--r-sm);
  font-family: var(--ff-gothic);
  font-size: 0.85rem;
  cursor: pointer;
  margin-left: auto;
}

/* Top-page banner (preview/prototype) */
.preview-banner {
  background: var(--c-champagne);
  color: var(--c-pine);
  text-align: center;
  font-family: var(--ff-mincho);
  font-size: 0.85rem;
  padding: 8px 16px;
  border-bottom: 1px solid var(--c-gold);
  letter-spacing: 0.06em;
}
.preview-banner strong { font-weight: 700; }

/* -----------------------------------------------------------------
   4. Layout
----------------------------------------------------------------- */
.page {
  max-width: var(--content-w);
  margin: 0 auto;
  padding: 48px var(--gutter) 72px;
}
.page--wide { max-width: var(--content-w-wide); }

.breadcrumb {
  max-width: var(--content-w);
  margin: 0 auto;
  padding: 14px var(--gutter) 0;
  font-family: var(--ff-mincho);
  font-size: 0.82rem;
  color: var(--c-charcoal);
  letter-spacing: 0.04em;
}
.breadcrumb a { color: var(--c-charcoal); }
.breadcrumb__sep::before { content: " ／ "; color: var(--c-mute); margin: 0 4px; }

/* -----------------------------------------------------------------
   5. Hero (top page)
----------------------------------------------------------------- */
.hero {
  background: var(--c-pine);
  color: var(--c-ivory);
  text-align: center;
  padding: 72px var(--gutter) 56px;
  border-bottom: 2px solid var(--c-gold);
}
.hero__kicker {
  font-family: var(--ff-serif);
  font-style: italic;
  letter-spacing: 0.3em;
  color: var(--c-gold);
  font-size: 0.78rem;
  margin: 0 0 14px;
}
.hero__title {
  font-family: var(--ff-mincho);
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 600;
  letter-spacing: 0.18em;
  margin: 0;
}
.hero__title em {
  font-style: normal;
  color: var(--c-crimson);
}
.hero__subtitle {
  font-family: var(--ff-mincho);
  color: var(--c-champagne);
  font-size: 1.05rem;
  margin: 16px 0 6px;
  letter-spacing: 0.1em;
}
.hero__catch {
  font-family: var(--ff-serif);
  font-style: italic;
  color: var(--c-gold);
  letter-spacing: 0.1em;
  font-size: 0.95rem;
  margin-top: 22px;
}

/* -----------------------------------------------------------------
   6. Section heading
----------------------------------------------------------------- */
.h-section {
  font-family: var(--ff-mincho);
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--c-pine);
  margin: 48px 0 18px;
  letter-spacing: 0.06em;
  border-left: 4px solid var(--c-gold);
  padding-left: 12px;
}
.h-sub {
  font-family: var(--ff-mincho);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--c-pine);
  margin: 32px 0 12px;
}
.h-sub::before { content: "◇ "; color: var(--c-gold); }
.h-sub--filled::before { content: "◆ "; color: var(--c-crimson); }

.lead {
  font-family: var(--ff-mincho);
  font-size: 1.02rem;
  color: var(--c-charcoal);
  line-height: 2;
}

/* -----------------------------------------------------------------
   7. Part cards (top page)
----------------------------------------------------------------- */
.part-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 22px;
  margin: 28px 0 12px;
}
.part-card {
  display: block;
  background: var(--c-paper);
  border: 1px solid var(--c-pine);
  border-top: 6px solid var(--c-gold);
  padding: 26px 22px 22px;
  text-decoration: none;
  color: inherit;
  box-shadow: var(--sh-card);
  transition: transform .15s ease, box-shadow .15s ease;
}
.part-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 30px -16px rgba(31,61,46,.35);
}
.part-card__kicker {
  font-family: var(--ff-serif);
  font-style: italic;
  letter-spacing: 0.2em;
  color: var(--c-gold-dark);
  font-size: 0.78rem;
  margin: 0 0 6px;
}
.part-card__num {
  font-family: var(--ff-mincho);
  font-size: 0.92rem;
  letter-spacing: 0.2em;
  color: var(--c-pine);
  margin: 0 0 4px;
}
.part-card__title {
  font-family: var(--ff-mincho);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--c-pine);
  margin: 0 0 8px;
}
.part-card__desc {
  font-size: 0.92rem;
  color: var(--c-charcoal);
  line-height: 1.85;
  margin: 0 0 12px;
}
.part-card__meta {
  font-size: 0.78rem;
  color: var(--c-gold-dark);
  font-family: var(--ff-mincho);
  letter-spacing: 0.12em;
}

/* -----------------------------------------------------------------
   8. How-to section (top page)
----------------------------------------------------------------- */
.howto {
  background: var(--c-sage);
  border: 1px solid var(--c-sage-deep);
  border-radius: var(--r-md);
  padding: 26px 26px 22px;
  margin: 28px 0;
}
.howto h3 {
  font-family: var(--ff-mincho);
  color: var(--c-pine);
  font-size: 1.2rem;
  margin: 0 0 12px;
}
.howto ol {
  margin: 0; padding-left: 1.4em;
  font-family: var(--ff-mincho);
  line-height: 1.9;
}
.howto li { margin: 6px 0; }
.howto li strong { color: var(--c-pine); }

/* -----------------------------------------------------------------
   9. CTA / Button
----------------------------------------------------------------- */
.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin: 26px 0;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  font-family: var(--ff-mincho);
  font-size: 0.98rem;
  letter-spacing: 0.06em;
  text-decoration: none;
  border-radius: var(--r-sm);
  border: 1px solid var(--c-pine);
  transition: background .15s ease, color .15s ease;
}
.btn--primary { background: var(--c-pine); color: var(--c-ivory); }
.btn--primary:hover { background: var(--c-pine-dark); color: var(--c-gold); }
.btn--ghost { background: transparent; color: var(--c-pine); }
.btn--ghost:hover { background: var(--c-sage); color: var(--c-pine-dark); }
.btn::after { content: "→"; color: var(--c-gold); font-family: var(--ff-serif); }
.btn--primary::after { color: var(--c-gold); }

/* -----------------------------------------------------------------
   10. Lecture list (lectures.html)
----------------------------------------------------------------- */
.lectures-section {
  margin-top: 36px;
  padding-top: 12px;
  border-top: 1px solid var(--c-gold);
}
.lectures-section__head {
  display: flex; align-items: baseline; gap: 14px;
  flex-wrap: wrap;
  margin: 12px 0 18px;
}
.lectures-section__head h2 {
  font-family: var(--ff-mincho);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--c-pine);
  margin: 0;
  letter-spacing: 0.06em;
}
.lectures-section__head .count {
  font-family: var(--ff-serif);
  font-style: italic;
  color: var(--c-gold-dark);
  font-size: 0.9rem;
}

.lecture-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}
.lecture-card {
  background: var(--c-paper);
  border: 1px solid var(--c-line);
  border-radius: var(--r-md);
  padding: 16px 18px;
  display: flex; flex-direction: column;
  gap: 6px;
  text-decoration: none;
  color: inherit;
  position: relative;
  transition: border-color .15s ease, box-shadow .15s ease, transform .15s ease;
}
.lecture-card:hover {
  border-color: var(--c-pine);
  box-shadow: var(--sh-card);
  transform: translateY(-1px);
}
.lecture-card--coming {
  opacity: 0.65;
  pointer-events: none;
  background: var(--c-sage);
}
.lecture-card--coming::before {
  content: "準備中";
  position: absolute; top: 10px; right: 10px;
  font-family: var(--ff-mincho);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  color: var(--c-mute);
  background: var(--c-paper);
  border: 1px solid var(--c-line);
  padding: 1px 8px;
  border-radius: 10px;
}
.lecture-card__top {
  display: flex; align-items: center; gap: 10px;
}
.lecture-card__num {
  font-family: var(--ff-serif);
  font-weight: 600;
  font-size: 1.6rem;
  color: var(--c-gold);
  line-height: 1;
  min-width: 2.2em;
}
.lecture-card__chapter {
  font-family: var(--ff-mincho);
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  color: var(--c-mute);
}
.lecture-card__title {
  font-family: var(--ff-mincho);
  font-size: 1.02rem;
  font-weight: 600;
  color: var(--c-pine);
  line-height: 1.55;
}
.lecture-card__meta {
  margin-top: 6px;
  display: flex; gap: 8px; flex-wrap: wrap;
  font-size: 0.78rem;
}

/* badges */
.badge {
  display: inline-flex; align-items: center;
  padding: 2px 9px;
  font-family: var(--ff-mincho);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  border-radius: 10px;
  border: 1px solid currentColor;
  white-space: nowrap;
}
.badge--high   { color: var(--c-high);   background: rgba(31,61,46,.06); }
.badge--medium { color: var(--c-medium); background: rgba(167,137,64,.10); }
.badge--low    { color: var(--c-low);    background: rgba(154,43,43,.06); }
.badge--review {
  color: var(--c-warn);
  background: rgba(183,118,42,.10);
  border-color: var(--c-warn);
}
.badge--review::before { content: "⚠ "; }
.badge--multi { color: var(--c-indigo); background: rgba(46,79,110,.06); }
.badge--draft { color: var(--c-mute); background: var(--c-paper); }
.badge--draft::before { content: "仮 "; }

/* -----------------------------------------------------------------
   11. Lecture page
----------------------------------------------------------------- */
.lecture-header {
  background:
    linear-gradient(180deg, var(--c-pine) 0%, var(--c-pine) 70%, transparent 100%),
    var(--c-paper);
  color: var(--c-ivory);
  padding: 40px var(--gutter) 36px;
  border-bottom: 1px solid var(--c-gold);
}
.lecture-header__inner {
  max-width: var(--content-w);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 24px;
  align-items: center;
}
.lecture-header__num {
  font-family: var(--ff-serif);
  font-size: 4rem;
  font-weight: 600;
  color: var(--c-gold);
  line-height: 1;
  text-align: center;
  border-right: 1px solid var(--c-gold);
  padding-right: 18px;
}
.lecture-header__chapter {
  font-family: var(--ff-mincho);
  font-size: 0.8rem;
  letter-spacing: 0.22em;
  color: var(--c-champagne);
  margin-bottom: 8px;
}
.lecture-header__title {
  font-family: var(--ff-mincho);
  font-size: clamp(1.4rem, 3vw, 1.8rem);
  font-weight: 600;
  margin: 0;
  color: var(--c-ivory);
  letter-spacing: 0.04em;
}
.lecture-header__title small {
  display: block;
  font-size: 0.6em;
  color: var(--c-champagne);
  font-weight: 400;
  letter-spacing: 0.06em;
  margin-top: 8px;
}

/* "この講で説明できるようになるギモン" */
.gimon-card {
  background: var(--c-champagne);
  border-left: 4px solid var(--c-gold);
  padding: 20px 22px 16px;
  margin: 32px 0;
  border-radius: var(--r-sm);
}
.gimon-card__label {
  font-family: var(--ff-mincho);
  font-size: 0.85rem;
  letter-spacing: 0.1em;
  color: var(--c-pine);
  font-weight: 700;
  margin: 0 0 8px;
}
.gimon-card ul {
  list-style: none; padding: 0; margin: 0;
  font-family: var(--ff-mincho);
  line-height: 1.9;
  font-size: 0.96rem;
}
.gimon-card li {
  padding: 4px 0 4px 1.4em;
  position: relative;
  border-top: 1px dashed var(--c-gold);
}
.gimon-card li:first-child { border-top: none; }
.gimon-card li::before {
  content: "Q.";
  position: absolute;
  left: 0;
  font-family: var(--ff-mincho);
  font-weight: 700;
  color: var(--c-gold-dark);
  font-size: 0.85em;
}

/* Lecture sections (intro / activity / knowledge / summary / check / think) */
.lec-section {
  margin: 36px 0;
}
.lec-section__tag {
  display: inline-block;
  font-family: var(--ff-mincho);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  color: var(--c-ivory);
  background: var(--c-pine);
  padding: 2px 12px;
  border-radius: 10px;
  margin-bottom: 12px;
}
.lec-section--activity .lec-section__tag { background: var(--c-gold-dark); }
.lec-section--check    .lec-section__tag { background: var(--c-indigo); }
.lec-section--think    .lec-section__tag { background: var(--c-crimson); }
.lec-section--summary  .lec-section__tag { background: var(--c-pine-dark); }

/* Teacher voice (先生の一言) */
.teacher-voice {
  border-left: 3px solid var(--c-gold);
  padding: 4px 18px;
  margin: 22px 0;
  font-family: var(--ff-mincho);
  color: var(--c-charcoal);
  line-height: 1.95;
  font-size: 0.97rem;
}
.teacher-voice::before {
  content: "市来先生から";
  display: block;
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  color: var(--c-gold-dark);
  font-weight: 700;
  margin-bottom: 4px;
}

/* Q block (single question) */
.q-block {
  background: var(--c-champagne);
  border-left: 3px solid var(--c-gold);
  padding: 16px 20px 14px;
  margin: 22px 0;
  border-radius: var(--r-sm);
}
.q-block__label {
  font-family: var(--ff-mincho);
  color: var(--c-pine);
  font-weight: 700;
  margin-right: 8px;
}
.q-block__body {
  font-family: var(--ff-mincho);
  font-size: 1.02rem;
  color: var(--c-sumi);
  line-height: 1.9;
}

/* Key terms inline */
.kt {
  color: var(--c-crimson);
  font-weight: 700;
}
.kt[data-note] {
  border-bottom: 1px dotted var(--c-crimson);
  cursor: help;
}
.kt[data-note]::after {
  content: "［" attr(data-note) "］";
  color: var(--c-charcoal);
  font-size: 0.82em;
  font-weight: 400;
  margin-left: 2px;
}
.st { color: var(--c-indigo); font-weight: 600; }

/* Key term list (用語まとめ枠) */
.term-list {
  border: 1px solid var(--c-pine);
  border-top: 4px solid var(--c-gold);
  background: var(--c-paper);
  padding: 18px 22px;
  margin: 20px 0;
  box-shadow: var(--sh-card);
}
.term-list h4 {
  font-family: var(--ff-mincho);
  font-size: 1rem;
  color: var(--c-pine);
  margin: 0 0 10px;
  letter-spacing: 0.06em;
}
.term-list dl {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 6px 14px;
  margin: 0;
  font-size: 0.94rem;
  line-height: 1.85;
}
.term-list dt {
  font-family: var(--ff-mincho);
  color: var(--c-crimson);
  font-weight: 700;
  white-space: nowrap;
}
.term-list dd { margin: 0; color: var(--c-sumi); }

/* Blackboard summary */
.blackboard {
  background: var(--c-pine);
  color: var(--c-ivory);
  border: 2px solid var(--c-gold);
  border-radius: var(--r-lg);
  padding: 22px 26px;
  margin: 28px 0;
  font-family: var(--ff-mincho);
  letter-spacing: 0.04em;
  line-height: 2;
}
.blackboard h4 {
  font-family: var(--ff-mincho);
  font-size: 1.2rem;
  color: var(--c-gold);
  margin: 0 0 12px;
  letter-spacing: 0.12em;
}
.blackboard .bb-key { color: var(--c-gold); font-weight: 700; }
.blackboard .bb-tag {
  display: inline-block;
  background: var(--c-champagne);
  color: var(--c-pine);
  padding: 1px 8px;
  margin-left: 6px;
  font-size: 0.78rem;
  border-radius: var(--r-sm);
}
.blackboard ul { margin: 8px 0 0; padding-left: 1.2em; }
.blackboard li { margin: 4px 0; }

/* Activity (具体例・ゲーム) */
.activity {
  background: var(--c-paper);
  border: 1px solid var(--c-gold);
  border-radius: var(--r-md);
  padding: 18px 22px 16px;
  margin: 20px 0;
}
.activity__head {
  display: flex; align-items: baseline; gap: 10px;
  margin-bottom: 10px;
}
.activity__head h4 {
  font-family: var(--ff-mincho);
  font-size: 1.04rem;
  color: var(--c-pine);
  margin: 0;
  letter-spacing: 0.04em;
}
.activity__head .tag {
  font-family: var(--ff-mincho);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  color: var(--c-gold-dark);
}
.activity table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  margin: 10px 0 0;
}
.activity th, .activity td {
  border: 1px solid var(--c-line);
  padding: 8px 10px;
  text-align: left;
  vertical-align: top;
  background: var(--c-paper);
}
.activity thead th {
  background: var(--c-champagne);
  font-family: var(--ff-mincho);
  color: var(--c-pine);
}
.activity .vote-options {
  font-family: var(--ff-mincho);
  letter-spacing: 0.1em;
  color: var(--c-charcoal);
}

/* Check (確認のポイント — 解説型：Q+Aを並べて見せる) */
.check-list {
  list-style: none; padding: 0; margin: 0;
}
.check-list > li {
  border-top: 1px solid var(--c-line);
  padding: 14px 0;
  font-family: var(--ff-mincho);
  line-height: 1.95;
}
.check-list > li:first-child { border-top: none; }
.check-list .q {
  font-weight: 700;
  color: var(--c-pine);
  display: block;
  margin-bottom: 4px;
}
.check-list .q::before {
  content: "Q ";
  color: var(--c-gold-dark);
  font-family: var(--ff-serif);
  font-weight: 700;
  margin-right: 2px;
}
.check-list .a {
  display: block;
  color: var(--c-sumi);
}
.check-list .a::before {
  content: "A ";
  color: var(--c-crimson);
  font-family: var(--ff-serif);
  font-weight: 700;
  margin-right: 2px;
}

/* Think (思考を深める問い — 解説型：問い＋市来先生の見立て) */
.discussion-card {
  background: var(--c-paper);
  border: 1px solid var(--c-pine);
  border-left: 4px solid var(--c-pine);
  border-radius: var(--r-sm);
  padding: 18px 22px 14px;
  margin: 16px 0;
}
.discussion-card__q {
  font-family: var(--ff-mincho);
  font-size: 1.02rem;
  color: var(--c-pine);
  font-weight: 700;
  margin: 0 0 10px;
}
.discussion-card__q::before {
  content: "問　";
  color: var(--c-gold-dark);
  font-weight: 700;
}
.discussion-card__commentary {
  font-family: var(--ff-mincho);
  font-size: 0.97rem;
  color: var(--c-sumi);
  line-height: 1.95;
  margin: 0;
}
.discussion-card__commentary::before {
  content: "考え方 ";
  display: block;
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  color: var(--c-gold-dark);
  font-weight: 700;
  margin-bottom: 4px;
}

/* Video placeholder & related */
.video-frame {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: var(--c-pine);
  border: 1px solid var(--c-gold);
  border-radius: var(--r-md);
  display: flex; align-items: center; justify-content: center;
  color: var(--c-champagne);
  font-family: var(--ff-mincho);
  letter-spacing: 0.08em;
  font-size: 0.95rem;
  text-align: center;
  padding: 16px;
}
.video-frame--placeholder {
  background:
    repeating-linear-gradient(45deg, var(--c-pine) 0 12px, var(--c-pine-dark) 12px 24px);
}
.video-meta {
  font-size: 0.78rem;
  color: var(--c-mute);
  font-family: var(--ff-mincho);
  margin-top: 6px;
  letter-spacing: 0.04em;
}

.video-sequence {
  margin: 24px 0 8px;
}
.video-sequence__title {
  font-family: var(--ff-mincho);
  font-size: 0.95rem;
  color: var(--c-pine);
  margin: 0 0 8px;
  letter-spacing: 0.06em;
}
.video-sequence__list {
  list-style: none; margin: 0; padding: 0;
  display: flex; flex-wrap: wrap; gap: 8px;
}
.video-sequence__list li {
  font-family: var(--ff-mincho);
  font-size: 0.85rem;
  background: var(--c-paper);
  border: 1px solid var(--c-line);
  padding: 6px 12px;
  border-radius: 20px;
  color: var(--c-charcoal);
}
.video-sequence__list li[aria-current="page"] {
  background: var(--c-pine);
  color: var(--c-ivory);
  border-color: var(--c-pine);
}
.video-sequence__list li a { color: inherit; text-decoration: none; }
.video-sequence__list li .order {
  color: var(--c-gold);
  font-family: var(--ff-serif);
  font-weight: 600;
  margin-right: 4px;
}

/* Notices */
.notice {
  background: var(--c-champagne);
  border-left: 4px solid var(--c-gold-dark);
  padding: 14px 18px;
  margin: 22px 0;
  font-size: 0.92rem;
  line-height: 1.85;
  border-radius: var(--r-sm);
}
.notice__title {
  font-family: var(--ff-mincho);
  font-weight: 700;
  color: var(--c-pine);
  margin: 0 0 4px;
  letter-spacing: 0.08em;
}
.notice ul { margin: 4px 0 0; padding-left: 1.2em; }
.notice--draft {
  background: rgba(167,137,64,.10);
  border-left-color: var(--c-medium);
}

/* -----------------------------------------------------------------
   12. Lecture page navigation
----------------------------------------------------------------- */
.lec-nav {
  margin-top: 56px;
  padding-top: 22px;
  border-top: 1px solid var(--c-gold);
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  font-family: var(--ff-mincho);
  font-size: 0.95rem;
}
.lec-nav__prev { text-align: left; }
.lec-nav__home { text-align: center; }
.lec-nav__next { text-align: right; }
.lec-nav a { color: var(--c-pine); text-decoration: none; padding: 6px 8px; }
.lec-nav a:hover { color: var(--c-gold-dark); }
.lec-nav__prev a::before { content: "← "; color: var(--c-gold); }
.lec-nav__next a::after  { content: " →"; color: var(--c-gold); }
.lec-nav__small {
  display: block;
  font-size: 0.72rem;
  color: var(--c-mute);
  letter-spacing: 0.1em;
  margin-bottom: 4px;
}

/* -----------------------------------------------------------------
   13. Footer
----------------------------------------------------------------- */
.site-footer {
  border-top: 2px solid var(--c-gold);
  background: var(--c-pine);
  color: var(--c-champagne);
  padding: 28px var(--gutter);
  text-align: center;
  font-size: 0.85rem;
  line-height: 1.85;
  letter-spacing: 0.04em;
}
.site-footer__catch {
  font-family: var(--ff-serif);
  font-style: italic;
  letter-spacing: 0.2em;
  display: block;
  margin-top: 6px;
  color: var(--c-gold);
  font-size: 0.85em;
}
.site-footer a { color: var(--c-champagne); }

/* -----------------------------------------------------------------
   14. Misc helpers
----------------------------------------------------------------- */
.muted { color: var(--c-mute); }
.tmp::after {
  content: " 仮";
  display: inline-block;
  margin-left: 4px;
  padding: 0 6px;
  font-size: 0.62em;
  font-family: var(--ff-mincho);
  letter-spacing: 0.1em;
  border: 1px solid var(--c-medium);
  color: var(--c-medium);
  border-radius: 10px;
  vertical-align: middle;
}

/* -----------------------------------------------------------------
   15. Responsive
----------------------------------------------------------------- */
@media (max-width: 720px) {
  .site-nav { display: none; width: 100%; order: 3; }
  .site-nav.is-open { display: block; }
  .site-nav__list { flex-direction: column; gap: 10px; padding-top: 6px; }
  .nav-toggle { display: inline-block; }
  .hero { padding: 56px var(--gutter) 44px; }
  .hero__title { letter-spacing: 0.12em; }
  .lecture-header__inner { grid-template-columns: 64px 1fr; gap: 14px; }
  .lecture-header__num { font-size: 2.6rem; padding-right: 12px; }
  .lec-nav { grid-template-columns: 1fr; text-align: center; }
  .lec-nav__prev, .lec-nav__home, .lec-nav__next { text-align: center; }
  .term-list dl { grid-template-columns: 1fr; gap: 2px 0; }
  .term-list dt { margin-top: 6px; }
}