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

:root {
  --green-50:  oklch(97% 0.020 235);
  --green-100: oklch(93% 0.045 235);
  --green-200: oklch(87% 0.075 235);
  --green-400: oklch(68% 0.135 235);
  --green-600: oklch(52% 0.145 235);
  --green-800: oklch(36% 0.105 235);
  --text-main: #333333;
  --text-mid:  #333333;
  --text-muted:#333333;
  --white: #ffffff;
  --sidebar-w: 300px;
  --radius: 12px;
  --shadow: 0 2px 12px oklch(0% 0 0 / 0.08);
  --font: 'Noto Sans JP', sans-serif;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  font-weight: 400;
  background: oklch(98.5% 0.012 235);
  color: var(--text-main);
  line-height: 1.8;
  font-size: 16px;
  display: flex;
  min-height: 100vh;
}

/* ─── SIDEBAR ─── */
.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  background: oklch(98.5% 0.012 235);
  position: fixed;
  top: 0; left: 0; bottom: 0;
  display: flex;
  flex-direction: column;
  z-index: 100;
  overflow-y: auto;
}

.sidebar__brand {
  padding: 60px 20px 20px;
  text-align: center;
}

.sidebar__logo-title {
  font-size: 16px;
  font-weight: 600;
  color: #333333;
  line-height: 1.6;
}

.sidebar__logo {
  margin-top: 12px;
  margin-bottom: 24px;
  filter: drop-shadow(0 4px 8px oklch(52% 0.14 220 / 0.35));
}

.sidebar__logo img {
  max-width: 100%;
  height: auto;
  display: block;
  opacity: 1;
  margin: 0 auto;
}

.sidebar__nav {
  padding: 16px 12px;
  flex: 1;
}

.sidebar__nav-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: .12em;
  color: var(--text-muted);
  text-transform: uppercase;
  padding: 0 8px;
  margin: 16px 0 6px;
}

.sidebar__nav-label:first-child { margin-top: 0; }

.sidebar__nav a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 10px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 400;
  color: var(--text-mid);
  transition: background .15s, color .15s;
  margin-bottom: 2px;
}

.sidebar__nav a:hover {
  background: var(--green-50);
  color: var(--green-800);
}

.sidebar__nav a.active {
  background: var(--green-100);
  color: var(--green-600);
  font-weight: 500;
}

.sidebar__cta {
  padding: 16px 12px;
}

.sidebar__cta a {
  display: block;
  text-align: center;
  background: var(--green-600);
  color: var(--white);
  border-radius: 8px;
  padding: 11px 16px;
  font-weight: 500;
  text-decoration: none;
  transition: background .15s;
}

.sidebar__cta a:hover { background: var(--green-800); }

/* ─── SIDEBAR OVERLAY ─── */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 98;
  background: oklch(0% 0 0 / 0.3);
}

.sidebar-overlay.open { display: block; }
.sidebar.open { transform: translateX(0); }

/* ─── PAGE WRAPPER ─── */
.page-wrap {
  margin-left: calc(var(--sidebar-w) + 50px);
  margin-right: 150px;
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.page-wrap > * { width: 100%; }

/* ─── TOPBAR ─── */
.topbar {
  display: none;
  position: sticky;
  top: 0;
  z-index: 99;
  background: var(--white);
  border-bottom: 1px solid var(--green-100);
  padding: 0 16px;
  height: 56px;
  align-items: center;
  justify-content: space-between;
}

.topbar__title {
  font-size: 14px;
  font-weight: 600;
}

.topbar__hamburger {
  display: flex;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 6px;
  border: none;
  background: none;
}

.topbar__hamburger span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--text-main);
  border-radius: 2px;
}

/* ─── HERO ─── */
.hero {
  background: url('../img/back.jpg') center center / cover no-repeat;
  padding: 96px 100px 220px 100px;
  box-shadow: var(--shadow);
  color: #ffffff;
  position: relative;
  overflow: hidden;
  text-align: center;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(160deg, rgba(0,8,30,0.18) 0%, rgba(0,20,70,0.42) 100%);
  pointer-events: none;
}

.hero__h1 {
  font-size: 78px;
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 28px;
  position: relative;
  letter-spacing: .04em;
  text-shadow: 0 4px 24px rgba(0, 8, 40, 0.7);
}

.hero__h1-small {
  display: inline;
  font-size: 42px;
  font-weight: 400;
  letter-spacing: .06em;
  margin-right: 55px;
  color: #ffffff;
  vertical-align: baseline;
  text-shadow: 0 4px 24px rgba(0, 8, 40, 0.7);
}

.hero__sub {
  font-size: 35px;
  margin: 0 -100px 8px;
  letter-spacing: .05em;
  position: relative;
  display: block;
  background: rgba(8, 55, 140, 0.58);
  padding: 16px 64px;
  border-top: 1px solid rgba(255,255,255,0.22);
  border-bottom: 1px solid rgba(255,255,255,0.22);
  backdrop-filter: blur(6px);
  text-shadow: 0 1px 10px rgba(0, 8, 40, 0.55);
  line-height: 1.75;
}

.hero__sub-en {
  font-size: 30px;
  color: #ffffff;
  display: inline-block;
  margin-left: 2px;
}

.hero__info {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 14px;
}

.hero__meta {
  position: absolute;
  left: 40px;
  bottom: 32px;
  z-index: 2;
  font-size: 19px;
  font-weight: 500;
  letter-spacing: .05em;
  text-shadow: 0 4px 24px rgba(0, 8, 40, 0.7);
  color: #ffffff;
}

.hero__meta-list {
  display: flex;
  flex-direction: column;
  gap: 1px;
}

.hero__meta-row {
  display: grid;
  grid-template-columns: 4em 1fr;
}

.hero__meta-row dt {
  white-space: nowrap;
}

.hero__meta-row dt span {
  display: inline-block;
  width: 3em;
  text-align: justify;
  text-align-last: justify;
}

.hero__meta-row dd {
  margin: 0;
  text-align: left;
}

.hero__en {
  font-size: 38px;
  font-weight: 500;
  font-family: 'Noto Serif JP', serif;
  font-style: italic;
  letter-spacing: .08em;
  text-shadow: 0 4px 24px rgba(0, 8, 40, 0.7);
  text-align: right;
  margin-right: -60px;
  color: #ffffff;
  position: relative;
}

.hero__lectures {
  display: flex;
  gap: 0;
  justify-content: center;
  margin-left: -60px;
  margin-right: -60px;
  margin-top: 20px;
  position: relative;
}

.hero__lecture {
  display: flex;
  flex-direction: column;
  text-align: right;
  border-right: 2px solid rgba(255, 255, 255, 0.3);
  padding: 0 24px;
  flex: 1;
}

.hero__lecture:last-child {
  border-right: none;
  padding-right: 0;
}

.hero__lecture-label {
  font-size: 18px;
  font-weight: 600;
  letter-spacing: .14em;
  color: #ffe066;
  text-transform: uppercase;
  margin-bottom: 6px;
  text-shadow: 0 4px 24px rgba(0, 8, 40, 0.7);
  text-align: left;
}

.hero__lecture-title {
  font-size: 20px;
  font-weight: 500;
  color: #ffffff;
  letter-spacing: .03em;
  line-height: 1.55;
  margin-bottom: 6px;
  text-shadow: 0 4px 24px rgba(0, 8, 40, 0.7);
  text-align: left;
}

.hero__lecture-speaker {
  margin-top: auto;
  font-weight: 400;
  color: #ffffff;
  letter-spacing: .06em;
  text-shadow: 0 4px 24px rgba(0, 8, 40, 0.7);
}

.hero__lecture-affiliation { font-size: 16px; }

.hero__lecture-name { font-size: 19px; }

.hero__btns {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  position: relative;
  justify-content: center;
}

/* ─── BUTTONS ─── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 11px 26px;
  border-radius: 8px;
  font-size: 13.5px;
  font-family: var(--font);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  border: none;
  transition: transform .15s, box-shadow .15s;
}

.btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px oklch(0% 0 0 / 0.15);
}

.btn--white { background: var(--white); color: var(--green-800); }
.btn--outline { background: transparent; border: 1.5px solid oklch(100% 0 0 / 0.6); color: var(--white); }

/* ─── MAIN CONTENT ─── */
.main-content {
  padding: 48px 48px 80px;
  width: 100%;
  background: var(--white);
  box-shadow: var(--shadow);
}

/* ─── ALERT ─── */
/* .alert {
  background: var(--green-50);
  border-left: 4px solid var(--green-600);
  border-radius: var(--radius);
  padding: 18px 22px;
  border: 1px solid var(--green-400);
  margin-bottom: 48px;
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.alert__text strong {
  color: var(--green-600);
  font-weight: 600;
}

.alert__text p {
  color: var(--text-mid);
  margin-top: 4px;
} */

/* ─── SECTION ─── */
.section { margin-bottom: 60px; }

.section__header {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 22px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--green-400);
}

.section__title {
  font-size: 19px;
  font-weight: 600;
  color: var(--text-main);
}

.section__en {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: .1em;
  text-transform: uppercase;
  font-weight: 400;
}

/* ─── NEWS ─── */
.news-list {
  display: flex;
  flex-direction: column;
}

.news-item {
  display: grid;
  grid-template-columns: 116px auto 1fr;
  align-items: start;
  gap: 14px;
  padding: 14px 0;
  border-bottom: 1px solid var(--green-400);
}

.news-item--hidden { display: none; }

.news-item__date {
  color: var(--text-muted);
  white-space: nowrap;
  padding-top: 2px;
}

.news-item__tag {
  display: inline-block;
  font-size: 10.5px;
  font-weight: 600;
  padding: 2px 10px;
  border-radius: 100px;
  white-space: nowrap;
}

.news-item__tag--new { background: var(--green-100); color: var(--green-600); }
.news-item__tag--info { background: oklch(95% 0.028 235); color: oklch(40% 0.12 235); }

.news-item__text {
  color: var(--text-mid);
  line-height: 1.75;
}

.news-item__text a { color: var(--green-600); text-decoration: none; }
.news-item__text a:hover { text-decoration: underline; }

.news__more-wrap {
  text-align: center;
  margin-top: 20px;
}

.news__more-btn {
  background: none;
  border: 1.5px solid var(--green-400);
  color: var(--green-600);
  font-family: var(--font);
  font-weight: 500;
  letter-spacing: .06em;
  padding: 8px 28px;
  border-radius: 100px;
  cursor: pointer;
  transition: background .15s, color .15s;
}

.news__more-btn:hover { background: var(--green-600); color: var(--white); }

/* ─── OVERVIEW TABLE ─── */
.overview-table-wrap {
  border: 1px solid var(--green-400);
  border-radius: var(--radius);
  overflow: hidden;
}

.overview-table {
  width: 100%;
  border-collapse: collapse;
}

.overview-table th,
.overview-table td {
  padding: 14px 20px;
  border-bottom: 1px solid var(--green-400);
  text-align: left;
  vertical-align: top;
  line-height: 1.7;
}

.overview-table tr:last-child th,
.overview-table tr:last-child td { border-bottom: none; }

.overview-table th {
  width: 140px;
  white-space: nowrap;
  background: var(--green-50);
  color: var(--text-main);
  font-weight: 500;
  border-right: 1px solid var(--green-400);
}

.overview-table td { color: var(--text-mid); }
.overview-table tr:hover td { background: oklch(98% 0.012 235); }

/* ─── PROGRAM OUTLINE ─── */
.program-outline {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 20px;
}

.program-card {
  border: 1px solid var(--green-400);
  border-radius: var(--radius);
  padding: 20px 22px;
  background: var(--white);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.program-block {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.program-block__label {
  display: inline-block;
  font-size: 16px;
  font-weight: 400;
  color: var(--green-600);
  background: var(--green-50);
  border: 1px solid var(--green-400);
  border-radius: 4px;
  padding: 2px 10px;
  margin-bottom: 4px;
  width: fit-content;
}

.program-block__speaker {
  text-align: right;
}

.program-block__sessions {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.program-block__sessions p {
  margin: 0;
}


/* ─── ARCHIVE ─── */
.archive-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}

.card {
  background: var(--white);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 26px;
  border: 1px solid var(--green-400);
}

.card__label {
  font-size: 10.5px;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--green-600);
  font-weight: 600;
  margin-bottom: 10px;
}

.card__title {
  font-weight: 600;
  margin-bottom: 14px;
}

.session-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.session-list li {
  color: var(--text-mid);
  padding: 8px 12px;
  background: var(--green-50);
  border-radius: 6px;
  border-left: 3px solid var(--green-400);
  line-height: 1.55;
}

.steps {
  list-style: none;
  counter-reset: step;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.steps li {
  counter-increment: step;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  color: var(--text-mid);
}

.steps li::before {
  content: counter(step);
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--green-600);
  color: var(--white);
  font-size: 11px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 1px;
  font-family: var(--font);
}

.steps__note {
  color: var(--text-muted);
  margin-top: 16px;
  padding-top: 12px;
  border-top: 1px solid var(--green-100);
}

/* ─── PURPOSE ─── */
.purpose-card {
  background: var(--white);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 34px 38px;
  border: 1px solid var(--green-400);
  position: relative;
  overflow: hidden;
}

.purpose-card p {
  color: var(--text-mid);
  line-height: 2;
  margin-bottom: 14px;
  text-indent: 1em;
}

.purpose-card p:last-of-type { margin-bottom: 0; }

.organizer {
  display: flex;
  width: fit-content;
  align-items: center;
  gap: 8px;
  margin-top: 20px;
  margin-left: auto;
  padding: 9px 16px;
  background: var(--green-50);
  border-radius: 8px;
  color: var(--text-mid);
}

.organizer strong {
  color: var(--text-main);
  font-weight: 500;
}

/* ─── RELATED ─── */
.related-grid {
  display: flex;
  flex-wrap: nowrap;
  gap: 12px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  padding-bottom: 8px;
}
.related-grid > * { flex: 0 0 auto; }

.related-item {
  background: var(--white);
  border: 1px solid var(--green-400);
  border-radius: 8px;
  padding: 9px 16px;
  color: var(--text-mid);
  text-decoration: none;
  transition: border-color .15s, color .15s;
  display: flex;
  align-items: center;
  gap: 6px;
}

.related-item:hover { border-color: var(--green-400); color: var(--green-600); }
.related-item::before { content: '\2192'; font-size: 11px; color: var(--green-400); }

.related-item--banner {
  padding: 0;
  border: none;
  background: transparent;
  border-radius: 0;
  gap: 0;
}
.related-item--banner::before { content: none; }
.related-item--banner img {
  display: block;
  width: 300px;
  height: auto;
}
.related-item--banner:hover { opacity: 0.85; color: inherit; }

/* ─── CONTACT ─── */
.contact-card {
  background:
    linear-gradient(to right, rgba(40, 100, 160, 0.90), rgba(80, 150, 200, 0.20)),
    url('../img/bridge.jpg') center 70% / cover no-repeat;
  color: var(--white);
  border-radius: var(--radius);
  padding: 48px 48px;
  min-height: 290px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.contact-card__title {
  font-weight: 500;
}

.contact-info {
  opacity: .95;
  line-height: 1.6;
}

.contact-info a { color: var(--white); }

.social-links { display: flex; gap: 10px; }


.social-btn {
  width: 46px;
  height: 46px;
  border-radius: 10px;
  background: oklch(100% 0 0 / 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  color: var(--white);
  transition: background .15s, transform .15s;
}

.social-btn svg {
  width: 24px;
  height: 24px;
  display: block;
}

.social-btn:hover { background: oklch(100% 0 0 / 0.28); transform: translateY(-2px); }

/* ─── FOOTER ─── */
footer {
  background: var(--green-800);
  box-shadow: var(--shadow);
  color: oklch(82% 0.03 152);
  text-align: center;
  padding: 26px 24px;
  font-size: 12px;
  line-height: 2;
  font-family: var(--font);
}


/* ─── RESPONSIVE ─── */

/* タブレット大（〜1280px）: 余白を縮めてコンテンツ幅を確保 */
@media (max-width: 1280px) {
  .page-wrap { margin-left: calc(var(--sidebar-w) + 24px); margin-right: 80px; }
  .hero { padding: 80px 72px 240px; }
  .hero__h1 { font-size: 64px; }
  .hero__h1-small { font-size: 36px; margin-right: 36px; }
  .hero__sub { margin: 0 -72px 16px; padding: 14px 48px; font-size: 24px; }
  .hero__en { font-size: 28px; margin-right: -32px; }
  .hero__meta { font-size: 17px; }
  .hero__lecture-name { font-size: 17px; }
}

/* タブレット横（〜1024px）: サイドバー表示のまま余白・文字を縮小 */
@media (max-width: 1024px) {
  .page-wrap { margin-left: calc(var(--sidebar-w) + 16px); margin-right: 24px; }
  .main-content { padding: 40px 36px 64px; }
  .hero { padding: 64px 48px 220px; }
  .hero__h1 { font-size: 54px; }
  .hero__h1-small { font-size: 28px; margin-right: 20px; letter-spacing: .04em; }
  .hero__sub { margin: 0 -48px 16px; padding: 12px 32px; font-size: 20px; }
  .hero__en { font-size: 24px; margin-right: -8px; }
  .hero__meta { left: 32px; bottom: 28px; font-size: 16px; }
  .hero__lecture-name { font-size: 16px; }
}

/* タブレット縦・モバイル（〜820px）: ハンバーガー化＋各部を最適化 */
@media (max-width: 820px) {
  .sidebar {
    transform: translateX(-100%);
    transition: transform .25s ease;
  }

  .sidebar.open {
    transform: translateX(0);
    box-shadow: 4px 0 24px oklch(0% 0 0 / 0.12);
  }

  .page-wrap { margin-left: 0; margin-right: 0; }
  .topbar { display: flex; }

  .hero { padding: 56px 24px 140px; margin-top: 0; }
  .hero__h1 { font-size: 40px; margin-bottom: 16px; }
  .hero__h1-small { font-size: 14px; letter-spacing: .3em; margin-right: 8px; display: block; margin-bottom: 6px; }
  .hero__sub { font-size: 15px; margin: 0 -24px 24px; padding: 14px 24px; }
  .hero__sub-en { display: block; margin-left: 0; margin-top: 4px; font-size: 24px; }
  .hero__en { font-size: 20px; margin-right: 0; }
  .hero__info { text-align: left; }
  .hero__lectures { flex-direction: column; gap: 16px; margin-left: 0; margin-right: 0; margin-top: 14px; }
  .hero__lecture { border-right: none; padding: 0 0 14px; border-bottom: 1px solid rgba(255,255,255,0.2); text-align: left; }
  .hero__lecture:last-child { border-bottom: none; padding-bottom: 0; }
  .hero__lecture-title { font-size: 13px; }
  .hero__lecture-affiliation { font-size: 13px; }
  .hero__lecture-name { font-size: 14px; }
  .hero__meta { left: 24px; bottom: 16px; font-size: 14px; }

  .main-content { padding: 32px 20px 56px; }
  .section__title { font-size: 17px; }

  .news-item {
    grid-template-columns: auto auto 1fr;
    gap: 8px 10px;
  }
  .news-item__date,
  .news-item__tag { grid-row: 1; }
  .news-item__text { grid-column: 1 / -1; }

  .overview-table th,
  .overview-table td { padding: 12px 14px; }
  .overview-table th { width: 110px; }

  .archive-grid { grid-template-columns: 1fr; }
  .contact-card { padding: 32px 24px; min-height: 0; }
  .purpose-card { padding: 24px 20px; }
}

/* スマホ（〜600px）: Hero・セクション縮小 */
@media (max-width: 600px) {
  .program-outline { grid-template-columns: 1fr; }
  .hero { padding: 44px 18px 120px; }
  .hero__h1 { font-size: 32px; }
  .hero__sub { font-size: 14px; margin: 0 -18px 20px; padding: 12px 18px; }
  .hero__en { font-size: 17px; }
  .hero__meta { left: 18px; bottom: 12px; font-size: 13px; }
  .hero__lecture-name { font-size: 13px; }
  .section { margin-bottom: 44px; }
  .section__header { gap: 8px; margin-bottom: 16px; }
  .related-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
    overflow-x: visible;
    padding-bottom: 0;
  }
  .related-item { font-size: 13px; padding: 8px 12px; }
  .related-item--banner img { width: 100%; height: auto; }
}

/* 小型スマホ（〜480px）: overview-table縦積み、Hero極小化 */
@media (max-width: 480px) {
  .overview-table,
  .overview-table tbody,
  .overview-table tr,
  .overview-table th,
  .overview-table td { display: block; width: 100%; }
  .overview-table th { border-right: none; border-bottom: none; padding: 10px 14px 4px; font-size: 13px; }
  .overview-table td { padding: 0 14px 12px; border-bottom: 1px solid var(--green-400); }
  .overview-table tr:last-child td { border-bottom: none; }

  .hero__h1 { font-size: 28px; }
  .hero__h1-small { font-size: 12px; }
  .contact-card { padding: 28px 20px; }
  .program-card { padding: 16px 18px; }
}