:root {
  --ink: #1b2430;
  --ink-soft: #4a5568;
  --paper: #ffffff;
  --paper-soft: #f5f7fa;
  --accent: #2f6f4f;
  --accent-soft: #e5f1ea;
  --border: #e2e6ea;
  --max-width: 880px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
}

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

a:hover {
  text-decoration: underline;
}

.wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

h1, h2 {
  line-height: 1.25;
  color: var(--ink);
}

h1 {
  font-size: 2rem;
  margin: 0 0 1.25rem;
}

h2 {
  font-size: 1.5rem;
  margin: 0 0 1rem;
}

.site-header {
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(180%) blur(6px);
  z-index: 10;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-top: 14px;
  padding-bottom: 14px;
  flex-wrap: wrap;
}

.brand {
  font-weight: 700;
  color: var(--ink);
  font-size: 1.05rem;
}

.brand:hover {
  text-decoration: none;
}

.main-nav {
  display: flex;
  gap: 20px;
}

.main-nav a {
  color: var(--ink-soft);
  font-weight: 500;
}

.hero {
  padding: 56px 0 40px;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0 0 12px;
}

.hero p {
  color: var(--ink-soft);
  margin: 0 0 1rem;
}

.section {
  padding: 40px 0;
  border-top: 1px solid var(--border);
}

.section-note {
  color: var(--ink-soft);
  margin-top: -0.5rem;
}

.involve-list {
  padding-left: 1.2rem;
  margin: 0 0 24px;
}

.involve-list li {
  margin-bottom: 0.6rem;
}

.calendar-embed {
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  background: var(--paper-soft);
}

.calendar-embed iframe {
  display: block;
  width: 100%;
  height: 500px;
}

.library-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 16px;
}

.library-cover {
  aspect-ratio: 2 / 3;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent-soft), var(--paper-soft));
  border: 1px dashed var(--border);
}

.link-grid {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 10px 20px;
}

.link-grid li {
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
}

.link-list {
  padding-left: 1.2rem;
  margin: 0 0 32px;
}

.link-list li {
  margin-bottom: 0.5rem;
}

.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 24px;
}

.book {
  color: var(--ink);
  display: block;
}

.book:hover {
  text-decoration: none;
}

.book:hover .book-title {
  text-decoration: underline;
}

.book .library-cover {
  margin-bottom: 10px;
}

.book-title {
  font-weight: 700;
  margin: 0 0 2px;
}

.book-subtitle,
.book-author {
  color: var(--ink-soft);
  font-size: 0.9rem;
  margin: 0 0 2px;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.video-embed {
  position: relative;
  border-radius: 12px;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: var(--paper-soft);
  border: 1px solid var(--border);
}

.video-embed iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

.social-links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

.social-links a {
  font-weight: 600;
  padding: 10px 18px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
}

.social-links a:hover {
  text-decoration: none;
  background: var(--accent);
  color: var(--paper);
}

.site-footer {
  padding: 28px 0 48px;
  color: var(--ink-soft);
  font-size: 0.9rem;
}

@media (max-width: 560px) {
  h1 {
    font-size: 1.6rem;
  }

  .hero {
    padding: 40px 0 28px;
  }

  .calendar-embed iframe {
    height: 380px;
  }
}