:root {
  color-scheme: light;
  --ink: #151b2b;
  --muted: #667085;
  --line: #dfe3ec;
  --paper: #ffffff;
  --canvas: #f4f6fb;
  --accent: #4255e7;
  --accent-soft: #e9ecff;
  --video: #8a3ffc;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--canvas); color: var(--ink); }
a { color: inherit; }
.shell { width: min(100% - 32px, 760px); margin-inline: auto; }
.site-header { padding: 22px 0 14px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; font-weight: 800; }
.brand-mark { display: grid; width: 34px; height: 34px; place-items: center; border-radius: 10px; background: var(--ink); color: white; font-size: 18px; }
.eyebrow { margin: 0 0 8px; color: var(--accent); font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
h1 { margin: 0; font-size: clamp(2rem, 8vw, 3.6rem); line-height: 1.02; letter-spacing: -.045em; }
h2 { margin: 36px 0 14px; font-size: 1.35rem; letter-spacing: -.02em; }
h3 { margin: 0; font-size: 1.05rem; line-height: 1.3; }
.intro { margin: 16px 0 28px; color: var(--muted); font-size: 1.05rem; line-height: 1.6; }
.summary { display: flex; gap: 8px; flex-wrap: wrap; margin: 18px 0 30px; }
.chip { border: 1px solid var(--line); border-radius: 999px; background: var(--paper); padding: 7px 11px; color: var(--muted); font-size: .82rem; font-weight: 700; }
.course-list, .article-list { display: grid; gap: 12px; padding: 0; list-style: none; }
.course-card, .article-card { display: block; padding: 18px; border: 1px solid var(--line); border-radius: 18px; background: var(--paper); text-decoration: none; box-shadow: 0 6px 22px rgba(21,27,43,.045); }
.course-card:hover, .article-card:hover { border-color: #aeb8ff; }
.course-card h2 { margin: 0; font-size: 1.18rem; }
.course-card p, .article-card p { margin: 8px 0 0; color: var(--muted); line-height: 1.5; }
.card-meta { display: flex; justify-content: space-between; gap: 12px; margin-top: 14px; color: var(--muted); font-size: .82rem; font-weight: 700; }
.back { display: inline-block; margin: 10px 0 24px; color: var(--accent); font-weight: 750; text-decoration: none; }
.article-head { padding: 24px 0 22px; border-bottom: 1px solid var(--line); }
.article-title { font-size: clamp(2rem, 8vw, 3.3rem); }
.article-meta { display: flex; gap: 8px; flex-wrap: wrap; margin: 16px 0 0; }
.tag { padding: 5px 9px; border-radius: 999px; background: var(--accent-soft); color: #2e3ec2; font-size: .78rem; font-weight: 750; }
.tag.video { background: #f0e8ff; color: var(--video); }
.prose { padding: 26px 0 56px; font-family: Georgia, "Times New Roman", serif; font-size: clamp(1.08rem, 4.7vw, 1.22rem); line-height: 1.78; }
.prose h2, .prose h3 { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; line-height: 1.2; }
.prose h2 { margin-top: 2.2em; }
.prose p { margin: 0 0 1.25em; }
.prose blockquote { margin: 1.5em 0; padding: 4px 0 4px 18px; border-left: 4px solid var(--accent); color: #465068; }
.prose img { display: block; max-width: 100%; height: auto; margin: 1.6em auto; border-radius: 16px; }
.prose a { color: #3044d8; text-decoration-thickness: 1px; text-underline-offset: 3px; overflow-wrap: anywhere; }
.prose pre { overflow-x: auto; padding: 16px; border-radius: 12px; background: var(--ink); color: white; font-size: .9rem; }
.video-link { display: block; margin: 20px 0; padding: 16px 18px; border-radius: 14px; background: var(--ink); color: white; text-align: center; text-decoration: none; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; font-weight: 800; }
.memberships { margin: 22px 0 0; padding: 14px 16px; border-radius: 14px; background: var(--accent-soft); font-size: .9rem; line-height: 1.55; }
.memberships a { color: #2e3ec2; font-weight: 750; }
.site-footer { padding: 30px 0 44px; border-top: 1px solid var(--line); color: var(--muted); font-size: .8rem; }
@media (min-width: 680px) {
  .course-list { grid-template-columns: 1fr 1fr; }
  .course-card, .article-card { padding: 22px; }
  .site-header { padding-top: 34px; }
}
@media (prefers-reduced-motion: no-preference) {
  .course-card, .article-card { transition: transform .16s ease, border-color .16s ease, box-shadow .16s ease; }
  .course-card:hover, .article-card:hover { transform: translateY(-2px); box-shadow: 0 10px 28px rgba(21,27,43,.08); }
}