/* ── Variables ────────────────────────────────────────── */
:root {
  --primary:       #1c3557;
  --primary-dark:  #0f1e35;
  --accent:        #2e6da4;
  --accent-light:  #e8f2fb;
  --teal:          #0d7377;
  --teal-dark:     #0a5f62;
  --teal-light:    #e0f4f4;
  --gold:          #b8922a;
  --gold-light:    #fdf6e3;
  --text:          #1a202c;
  --text-muted:    #4a5568;
  --border:        #cbd5e0;
  --bg:            #f7f9fc;
  --white:         #ffffff;
  --radius:        6px;
  --nav-height:    60px;
  --content-width: 880px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Inter', 'Segoe UI', system-ui, -apple-system, sans-serif;
  font-size: 15px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--teal); text-decoration: underline; }

/* ── Hamburger controls ───────────────────────────────── */
.nav-toggle-input { display: none; }
.nav-toggle-btn   { display: none; }
.nav-overlay      { display: none; }
.nav-close-btn    { display: none; }

/* ── Top Navigation ───────────────────────────────────── */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--primary);
  z-index: 100;
  box-shadow: 0 2px 16px rgba(0,0,0,.25);
}
.site-header-inner {
  max-width: var(--content-width);
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  gap: 1.5rem;
}
.header-logo {
  display: flex;
  align-items: center;
  gap: .5rem;
  color: #fff;
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: .04em;
  flex-shrink: 0;
}
.header-logo:hover { color: #fff; text-decoration: none; opacity: .85; }
.header-nav {
  display: flex;
  align-items: center;
  gap: .1rem;
  margin-left: auto;
}
.header-nav a {
  color: rgba(255,255,255,.78);
  font-size: .82rem;
  font-weight: 500;
  padding: .38rem .72rem;
  border-radius: 4px;
  transition: background .15s, color .15s;
}
.header-nav a:hover {
  color: #fff;
  background: rgba(255,255,255,.12);
  text-decoration: none;
}

/* ── Hero ─────────────────────────────────────────────── */
.hero {
  position: relative;
  min-height: 68vh;
  background-image: url(images/kobe.jpg);
  background-size: cover;
  background-position: center;
  display: flex;
  align-items: center;
  padding-top: var(--nav-height);
  overflow: hidden;
}

/* 写真に重ねるグラデーション（提案Aのオーバーレイ） */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    130deg,
    rgba(15, 30, 53, 0.84) 0%,
    rgba(15, 30, 53, 0.68) 55%,
    rgba(13, 115, 119, 0.48) 100%
  );
}

/* λウォーターマーク（提案C） */
.hero::after {
  content: '\03BB';
  position: absolute;
  right: -1.5rem;
  bottom: -3.5rem;
  font-family: 'Playfair Display', Georgia, serif;
  font-size: clamp(14rem, 28vw, 26rem);
  font-style: italic;
  color: rgba(255,255,255,0.045);
  line-height: 1;
  pointer-events: none;
  user-select: none;
  -webkit-user-select: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 4rem 1.5rem 3.5rem;
  width: 100%;
}
.hero-eyebrow {
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .2em;
  color: var(--teal-light);
  margin-bottom: .9rem;
  opacity: .9;
}
.hero-title {
  font-family: 'Playfair Display', Georgia, serif;
  font-size: clamp(2rem, 4.5vw, 3.1rem);
  font-weight: 700;
  color: #fff;
  line-height: 1.22;
  margin-bottom: 1rem;
  text-shadow: 0 2px 12px rgba(0,0,0,.35);
}
.hero-meta {
  font-size: .98rem;
  color: rgba(255,255,255,.78);
  margin-bottom: 1.6rem;
  font-weight: 500;
  letter-spacing: .01em;
}
.hero-speakers {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: .4rem .7rem;
  margin-bottom: 2.2rem;
}
.hero-speakers-label {
  color: rgba(255,255,255,.5);
  font-size: .7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .12em;
  width: 100%;
  margin-bottom: .1rem;
}
.hero-speaker-item { color: rgba(255,255,255,.85); font-size: .88rem; }
.hero-speaker-sep  { color: rgba(255,255,255,.3); }
.hero-cta {
  display: inline-block;
  padding: .72rem 2rem;
  background: var(--teal);
  color: #fff;
  font-weight: 600;
  font-size: .88rem;
  border-radius: 30px;
  letter-spacing: .03em;
  transition: background .2s, transform .15s, box-shadow .2s;
  box-shadow: 0 4px 14px rgba(13,115,119,.45);
}
.hero-cta:hover {
  background: var(--teal-dark);
  color: #fff;
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(13,115,119,.55);
}

/* ── Main content ─────────────────────────────────────── */
.main-content {
  max-width: var(--content-width);
  margin: 0 auto;
  background: var(--white);
  padding: 2.5rem 1.5rem 4rem;
  box-shadow: 0 0 40px rgba(0,0,0,.06);
}

/* ── Key facts bar ────────────────────────────────────── */
.key-facts-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 2rem;
}
.kf-item {
  flex: 1;
  min-width: 150px;
  background: var(--bg);
  padding: .85rem 1rem;
  display: flex;
  flex-direction: column;
  gap: .2rem;
}
.kf-label {
  font-size: .66rem;
  text-transform: uppercase;
  letter-spacing: .09em;
  color: var(--text-muted);
  font-weight: 600;
}
.kf-value { font-size: .88rem; font-weight: 500; color: var(--text); line-height: 1.5; }
.kf-sub   { font-size: .76rem; color: var(--text-muted); line-height: 1.4; }

/* ── Section headings ─────────────────────────────────── */
.section-heading {
  display: flex;
  align-items: center;
  gap: .6rem;
  font-family: 'Playfair Display', Georgia, serif;
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--primary);
  padding-bottom: .45rem;
  border-bottom: 2px solid var(--accent);
  margin: 2.2rem 0 1rem;
}
.section-heading::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 1.1em;
  background: var(--teal);
  border-radius: 2px;
  flex-shrink: 0;
}

/* ── Invited speakers ─────────────────────────────────── */
.invited-speakers {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  margin: 1rem 0;
}
.invited-chip {
  background: var(--gold-light);
  border: 1px solid #deb96a;
  border-radius: var(--radius);
  padding: .55rem 1rem;
  font-size: .88rem;
}
.invited-chip .chip-name { font-weight: 600; color: var(--primary); }
.invited-chip .chip-aff  { color: var(--text-muted); font-size: .82rem; }

/* ── Topics list ──────────────────────────────────────── */
.topics-list { list-style: none; margin: .5rem 0; }
.topics-list li {
  padding: .35rem 0 .35rem 1.2rem;
  position: relative;
  font-size: .92rem;
  border-bottom: 1px solid var(--bg);
}
.topics-list li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--teal);
  font-size: .75rem;
  top: .42rem;
}

/* ── Important dates ──────────────────────────────────── */
.dates-table { width: 100%; border-collapse: collapse; font-size: .9rem; }
.dates-table tr { border-bottom: 1px solid var(--border); }
.dates-table tr:last-child { border-bottom: none; }
.dates-table td { padding: .55rem .6rem; vertical-align: top; }
.dates-table .dt-name { color: var(--text-muted); width: 55%; }
.dates-table .dt-date { font-weight: 500; }
.dates-table .dt-date.done s { color: #aaa; font-weight: 400; }

/* ── Registration ─────────────────────────────────────── */
.reg-link {
  display: inline-block;
  margin: .5rem 0;
  padding: .6rem 1.6rem;
  background: var(--teal);
  color: #fff;
  border-radius: 30px;
  font-size: .88rem;
  font-weight: 600;
  transition: background .15s;
  box-shadow: 0 3px 10px rgba(13,115,119,.35);
}
.reg-link:hover { background: var(--teal-dark); text-decoration: none; color: #fff; }
.fee-table { border-collapse: collapse; margin-top: .6rem; font-size: .88rem; }
.fee-table td { padding: .3rem .8rem .3rem 0; vertical-align: top; }
.fee-table .fee-label { color: var(--text-muted); }
.fee-table .fee-price { font-weight: 600; }

/* ── Program: Timeline （提案E） ──────────────────────── */
.program-day {
  margin-bottom: 2rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.program-day-header {
  background: var(--primary);
  color: #fff;
  padding: .7rem 1.4rem;
  font-family: 'Playfair Display', Georgia, serif;
  font-size: .95rem;
  font-weight: 600;
  letter-spacing: .02em;
}

.program-timeline {
  position: relative;
  padding: .8rem 1.4rem .8rem 1.4rem;
}

/* タイムライン縦線: 時刻列(4rem) + gap(1.4rem) → 中心 = 1.4 + 4 + 0.7 = 6.1rem */
.program-timeline::before {
  content: '';
  position: absolute;
  left: 6.1rem;
  top: 1.5rem;
  bottom: 1.5rem;
  width: 2px;
  background: linear-gradient(
    to bottom,
    transparent,
    var(--border) 8%,
    var(--border) 92%,
    transparent
  );
}

/* セッション・イベント: 2カラムグリッド */
.program-session,
.program-event {
  display: grid;
  grid-template-columns: 4rem 1fr;
  gap: 0 1.4rem;
  margin-bottom: .7rem;
  position: relative;
}

/* ドット（タイムライン交点） */
.program-session::after,
.program-event::after {
  content: '';
  position: absolute;
  left: 5.75rem;
  top: .6rem;
  width: .7rem;
  height: .7rem;
  border-radius: 50%;
  background: var(--white);
  border: 2px solid var(--accent);
  z-index: 1;
}
.program-event::after {
  width: .5rem;
  height: .5rem;
  left: 5.85rem;
  top: .68rem;
  border-color: var(--border);
}

/* 時刻（左カラム） */
.session-time-col {
  font-family: 'Courier New', monospace;
  font-size: .7rem;
  font-weight: 700;
  color: var(--accent);
  text-align: right;
  padding-top: .5rem;
  line-height: 1.3;
}
.event-time-col {
  font-family: 'Courier New', monospace;
  font-size: .68rem;
  color: var(--text-muted);
  text-align: right;
  padding-top: .5rem;
}

/* セッション本体（右カラム） */
.session-body {
  border-left: 2px solid var(--accent-light);
  padding: .4rem 0 .6rem .85rem;
}
.session-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .2rem .7rem;
  margin-bottom: .45rem;
  align-items: baseline;
}
.session-name {
  font-weight: 600;
  font-size: .88rem;
  color: var(--primary);
}
.session-chair {
  font-size: .78rem;
  color: var(--text-muted);
}

/* イベント本体 */
.event-body {
  padding: .4rem 0 .4rem .85rem;
  border-left: 2px solid var(--border);
  font-size: .88rem;
  color: var(--text-muted);
  font-style: italic;
}

/* トーク一覧 */
.talks-list { list-style: none; padding: 0; margin: 0; }
.talk-item {
  padding: .42rem 0 .42rem .8rem;
  border-bottom: 1px solid rgba(203,213,224,.4);
  position: relative;
}
.talk-item:last-child { border-bottom: none; }
.talk-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: .78rem;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--border);
}
.talk-item.invited-talk {
  background: var(--gold-light);
  border-left: 3px solid var(--gold);
  padding-left: .8rem;
}
.talk-item.invited-talk::before { display: none; }
.talk-author { font-weight: 600; font-size: .88rem; color: var(--text); }
.talk-title  { font-style: italic; color: var(--text-muted); font-size: .86rem; }

.talk-badge {
  display: inline-block;
  font-size: .68rem;
  padding: .08rem .4rem;
  border-radius: 3px;
  font-weight: 700;
  margin-right: .3rem;
  vertical-align: middle;
}
.badge-online  { background: #dbeafe; color: #1e40af; }
.badge-no-abs  { background: #fee2e2; color: #991b1b; }
.badge-invited { background: var(--gold-light); color: var(--gold); border: 1px solid #deb96a; }

/* ── Proceedings ──────────────────────────────────────── */
.proceedings-block {
  display: flex;
  align-items: flex-start;
  gap: 1.5rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  font-size: .9rem;
}
.proceedings-block img { flex-shrink: 0; width: 100px; }

/* ── Online Proceedings ───────────────────────────────── */
.online-proc-block {
  background: var(--teal-light);
  border: 1px solid #9ed0d0;
  border-radius: var(--radius);
  padding: .8rem 1.2rem;
  font-size: .9rem;
}
.online-proc-block a { font-weight: 600; color: var(--teal); }

/* ── PC Members ───────────────────────────────────────── */
.pc-columns { columns: 2; column-gap: 2rem; list-style: none; }
.pc-columns li {
  font-size: .88rem;
  padding: .22rem 0;
  break-inside: avoid;
  border-bottom: 1px solid rgba(203,213,224,.4);
}
.pc-name { font-weight: 500; }
.pc-aff  { color: var(--text-muted); font-size: .8rem; }

/* ── Sponsors ─────────────────────────────────────────── */
.sponsor-list { list-style: none; }
.sponsor-list li { padding: .5rem 0; font-size: .88rem; border-bottom: 1px solid var(--border); }
.sponsor-list li:last-child { border-bottom: none; }

/* ── Archives ─────────────────────────────────────────── */
.archive-section { margin-bottom: 1rem; }
.archive-section h3 {
  font-size: .82rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: .5rem;
}
.chip-group { display: flex; flex-wrap: wrap; gap: .35rem; }
.chip-group a {
  display: inline-block;
  padding: .22rem .65rem;
  background: var(--accent-light);
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: .8rem;
  color: var(--accent);
  transition: background .15s, color .15s;
}
.chip-group a:hover { background: var(--accent); color: #fff; text-decoration: none; }
.chip-dead {
  display: inline-block;
  padding: .22rem .65rem;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: .8rem;
  color: var(--text-muted);
}

/* ── Code of Conduct ──────────────────────────────────── */
.coc-section h3 { font-size: .95rem; color: var(--primary); font-weight: 600; margin: 1rem 0 .4rem; }
.coc-section p  { font-size: .88rem; margin-bottom: .6rem; color: var(--text-muted); }

/* ── Contact ──────────────────────────────────────────── */
.contact-block {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: .9rem 1.2rem;
  font-size: .9rem;
}

/* ── Footer ───────────────────────────────────────────── */
.site-footer {
  background: var(--primary-dark);
  padding: 3rem 1.5rem 2rem;
}
.footer-inner {
  max-width: var(--content-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 2rem 3rem;
  align-items: start;
}
.footer-brand {
  display: flex;
  align-items: center;
  gap: .8rem;
}
.footer-conf-id {
  font-size: 1.05rem;
  font-weight: 700;
  color: rgba(255,255,255,.9);
  letter-spacing: .04em;
}
.footer-conf-long {
  font-size: .76rem;
  color: rgba(255,255,255,.4);
  max-width: 15rem;
  line-height: 1.5;
  margin-top: .15rem;
}
.footer-archives-area {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem 2.5rem;
}
.footer-archive-col h4 {
  font-size: .68rem;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: rgba(255,255,255,.38);
  margin-bottom: .5rem;
}
.footer-chips.chip-group a {
  background: rgba(255,255,255,.09);
  border: 1px solid rgba(255,255,255,.12);
  color: rgba(255,255,255,.6);
  font-size: .75rem;
}
.footer-chips.chip-group a:hover {
  background: rgba(255,255,255,.18);
  color: #fff;
}
.footer-chips .chip-dead {
  background: rgba(255,255,255,.04);
  border: 1px solid rgba(255,255,255,.08);
  color: rgba(255,255,255,.25);
  font-size: .75rem;
}

/* ── Mobile drawer ────────────────────────────────────── */
.mobile-drawer {
  position: fixed;
  top: 0;
  right: 0;
  width: 270px;
  height: 100vh;
  background: var(--primary);
  z-index: 250;
  transform: translateX(100%);
  transition: transform .25s ease;
  overflow-y: auto;
  padding-bottom: 2rem;
  box-shadow: -4px 0 20px rgba(0,0,0,.25);
}
.nav-toggle-input:checked ~ .mobile-drawer {
  transform: translateX(0);
}
.mobile-drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.2rem;
  border-bottom: 1px solid rgba(255,255,255,.1);
  min-height: var(--nav-height);
}
.drawer-conf-name {
  color: rgba(255,255,255,.9);
  font-weight: 700;
  font-size: 1rem;
  letter-spacing: .04em;
}
.mobile-drawer-links { padding: .5rem 0; }
.mobile-drawer-links a {
  display: block;
  padding: .6rem 1.4rem;
  color: rgba(255,255,255,.75);
  font-size: .88rem;
  border-left: 3px solid transparent;
  transition: background .15s, color .15s, border-color .15s;
}
.mobile-drawer-links a:hover {
  color: #fff;
  background: rgba(255,255,255,.08);
  border-left-color: var(--teal);
  text-decoration: none;
}
.mobile-drawer-archives {
  padding: .8rem 1.2rem;
  border-top: 1px solid rgba(255,255,255,.08);
  margin-top: .5rem;
}
.drawer-archive-label {
  font-size: .68rem;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: rgba(255,255,255,.35);
  margin-bottom: .5rem;
}
.mobile-drawer-archives .chip-group a {
  background: rgba(255,255,255,.1);
  border: none;
  color: rgba(255,255,255,.65);
  font-size: .72rem;
}
.mobile-drawer-archives .chip-group a:hover {
  background: rgba(255,255,255,.2);
  color: #fff;
}
.mobile-drawer-archives .chip-dead {
  background: rgba(255,255,255,.05);
  border: none;
  color: rgba(255,255,255,.25);
  font-size: .72rem;
}

/* ── Responsive ───────────────────────────────────────── */
@media (max-width: 820px) {
  /* ≡ボタン表示 */
  .nav-toggle-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: rgba(255,255,255,.13);
    color: #fff;
    font-size: 1.5rem;
    line-height: 1;
    border-radius: 6px;
    cursor: pointer;
    margin-left: auto;
    user-select: none;
    -webkit-user-select: none;
    flex-shrink: 0;
    transition: background .15s;
  }
  .nav-toggle-btn:hover { background: rgba(255,255,255,.22); }

  /* デスクトップナビ非表示 */
  .header-nav { display: none; }

  /* 閉じるボタン */
  .nav-close-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    color: rgba(255,255,255,.6);
    font-size: 1rem;
    cursor: pointer;
    border-radius: 4px;
    transition: background .15s, color .15s;
    user-select: none;
    -webkit-user-select: none;
  }
  .nav-close-btn:hover { background: rgba(255,255,255,.1); color: #fff; }

  /* バックドロップ */
  .nav-overlay {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,.45);
    z-index: 200;
    opacity: 0;
    pointer-events: none;
    transition: opacity .25s ease;
  }
  .nav-toggle-input:checked ~ .nav-overlay {
    opacity: 1;
    pointer-events: auto;
  }

  /* ヒーロー */
  .hero { min-height: 56vh; }
  .hero::after { font-size: 10rem; right: -.5rem; bottom: -2rem; }

  /* メインコンテンツ */
  .main-content { padding: 1.8rem 1rem 3rem; }

  /* タイムライン: 時刻列を縮小 */
  .program-timeline::before { left: 4.6rem; }
  .program-session,
  .program-event { grid-template-columns: 3.2rem 1fr; gap: 0 1.2rem; }
  .program-session::after { left: 4.3rem; }
  .program-event::after  { left: 4.4rem; }

  /* PC委員 */
  .pc-columns { columns: 1; }

  /* フッター */
  .footer-inner { grid-template-columns: 1fr; gap: 1.5rem; }
  .footer-archives-area { flex-direction: column; gap: 1rem; }
}

@media (max-width: 500px) {
  .hero-title { font-size: 1.65rem; }
  .hero::after { display: none; }
  .proceedings-block { flex-direction: column; }
  .section-heading { font-size: 1.05rem; }

  /* タイムライン: 極小画面は縦線・ドット非表示、シンプルなスタック */
  .program-timeline { padding: .5rem .8rem; }
  .program-timeline::before { display: none; }
  .program-session::after,
  .program-event::after { display: none; }
  .program-session,
  .program-event {
    grid-template-columns: 1fr;
    margin-bottom: 1rem;
    padding-bottom: .8rem;
    border-bottom: 1px solid var(--border);
  }
  .session-time-col,
  .event-time-col {
    text-align: left;
    font-size: .7rem;
    color: var(--teal);
    padding-top: 0;
    margin-bottom: .2rem;
  }
  .session-body { border-left: none; padding-left: 0; }
  .event-body   { border-left: none; padding-left: 0; }

  .key-facts-bar { flex-direction: column; gap: 0; }
  .kf-item { border-bottom: 1px solid var(--border); }
  .kf-item:last-child { border-bottom: none; }
}