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

html, body {
  height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  background: #fff;
  color: #111;
  font-size: 15px;
  line-height: 1.6;
}

/* ── Layout ────────────────────────────────────── */

.wrapper {
  display: flex;
  min-height: 100vh;
  max-width: 860px;
  margin: 0 auto;
  padding: 64px 40px;
  gap: 80px;
}

/* ── Left sidebar ──────────────────────────────── */

.sidebar {
  width: 160px;
  flex-shrink: 0;
}

.site-name {
  font-size: 0.95rem;
  font-weight: 600;
  color: #111;
  display: block;
  margin-bottom: 24px;
  letter-spacing: 0.01em;
  text-decoration: none;
}

.site-name:hover { text-decoration: none; color: #111; }

nav {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

nav a {
  display: block;
  color: #0055cc;
  text-decoration: none;
  font-size: 0.9rem;
  padding: 2px 0;
}

nav a:hover { text-decoration: underline; }

nav a.active { color: #111; text-decoration: none; font-weight: 500; }

/* ── Main content ──────────────────────────────── */

.content {
  flex: 1;
  min-width: 0;
}

/* Home page */
.home-intro {
  font-size: 0.9rem;
  color: #555;
  max-width: 480px;
}

/* Inner pages */
.page h1 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 20px;
  color: #111;
}

.page h2 {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #888;
  margin: 28px 0 10px;
}

.page h2:first-of-type { margin-top: 0; }

.page p {
  font-size: 0.9rem;
  color: #333;
  margin-bottom: 12px;
  max-width: 520px;
}

/* Book lists */
.page ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.page ul li {
  font-size: 0.9rem;
  color: #222;
}

.page ul li .author {
  color: #888;
}

/* Thoughts post list */
.posts {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.posts li a {
  color: #0055cc;
  text-decoration: none;
  font-size: 0.9rem;
  display: block;
}

.posts li a:hover { text-decoration: underline; }

.posts li .meta {
  font-size: 0.8rem;
  color: #999;
  margin-top: 2px;
}

/* Teaching */
.course {
  margin-bottom: 28px;
}

.course h3 {
  font-size: 0.9rem;
  font-weight: 600;
  color: #111;
  margin-bottom: 2px;
}

.course .course-meta {
  font-size: 0.85rem;
  color: #888;
  margin-bottom: 5px;
}

.course p {
  font-size: 0.88rem;
  color: #444;
  max-width: 500px;
  margin-bottom: 4px;
}

.course a {
  font-size: 0.85rem;
  color: #0055cc;
  text-decoration: none;
}

.course a:hover { text-decoration: underline; }

/* ── Responsive ────────────────────────────────── */

@media (max-width: 600px) {
  .wrapper {
    flex-direction: column;
    gap: 32px;
    padding: 32px 20px;
  }
  .sidebar { width: 100%; }
  nav { flex-direction: row; flex-wrap: wrap; gap: 12px; }
}