:root {
  --black: #0a0a0a;
  --white: #ffffff;
  --gray-50: #f5f5f5;
  --gray-100: #eaeaea;
  --gray-300: #cfcfcf;
  --gray-700: #4a4a4a;
  --max-width: 1100px;
  --header-height: 64px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, 'Noto Sans TC', Arial, 'PingFang TC', 'Heiti TC', sans-serif;
  color: var(--black);
  background: var(--white);
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--white);
  border-bottom: 1px solid var(--gray-100);
  z-index: 1000;
}
.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 100%;
}
.brand {
  font-weight: 800;
  letter-spacing: 0.4px;
}
.nav a {
  margin-left: 20px;
  color: var(--black);
  text-decoration: none;
  font-weight: 600;
}
.nav a:hover { text-decoration: underline; }

main { margin-top: var(--header-height); }

/* Intro section with diagonal split */
.section-intro {
  position: relative;
  min-height: calc(100vh - var(--header-height));
  background: linear-gradient(135deg, var(--white) 0 50%, var(--black) 50% 100%);
  display: grid;
  place-items: center;
  overflow: hidden;
}
.intro-overlay { position: absolute; inset: 0; opacity: 0.04; background: repeating-linear-gradient(90deg, #0000 0 20px, #0001 20px 21px); }
.intro-grid {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  width: 100%;
  align-items: center;
}
.intro-left { display: grid; place-items: center; padding: 40px 0; }
.photo-wrap { display: grid; place-items: center; }
.photo-circle {
  width: min(56vw, 360px);
  height: min(56vw, 360px);
  border-radius: 50%;
  background: var(--gray-100);
  box-shadow: 0 0 0 12px rgba(255,255,255,0.8), 0 16px 40px rgba(0,0,0,0.25);
  background-image: url('https://images.unsplash.com/photo-1502685104226-ee32379fefbe?q=80&w=800&auto=format&fit=crop');
  background-size: cover;
  background-position: center;
}
.intro-right { color: var(--white); padding: 40px 0; }
.intro-title { margin: 0 0 12px; font-size: clamp(28px, 4vw, 44px); line-height: 1.15; }
.intro-text { margin: 0; color: #f0f0f0; font-size: 16px; line-height: 1.8; max-width: 46ch; }

/* Courses */
.section-courses { padding: 80px 0; background: var(--white); }
.section-title { margin: 0 0 24px; font-size: 28px; }
.courses-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.course-card {
  background: var(--gray-50);
  color: var(--black);
  padding: 20px;
  border-radius: 12px;
  outline: 1px solid var(--gray-100);
}
.course-card h3 { margin: 0 0 10px; }
.course-card ul { margin: 0; padding-left: 18px; }
.course-card li { margin: 6px 0; }

/* Timeline (Notion-like) */
.section-timeline { padding: 80px 0; background: var(--white); }
.timeline { position: relative; margin-left: 12px; }
.timeline:before {
  content: '';
  position: absolute;
  left: 6px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--gray-300);
}
.timeline-item { display: grid; grid-template-columns: 90px 1fr; gap: 20px; align-items: start; margin-bottom: 24px; }
.timeline-year { color: var(--gray-700); font-weight: 600; }
.timeline-content { position: relative; }
.timeline-dot { position: absolute; left: -31px; top: 10px; width: 12px; height: 12px; background: var(--black); border-radius: 50%; box-shadow: 0 0 0 4px var(--white), 0 0 0 6px var(--gray-300); }
.timeline-card { background: var(--gray-50); padding: 16px; border-radius: 10px; outline: 1px solid var(--gray-100); }
.timeline-heading { font-weight: 700; margin-bottom: 6px; }
.timeline-desc { color: var(--black); margin: 0; }

/* Responsive */
@media (max-width: 900px) {
  .intro-grid { grid-template-columns: 1fr; gap: 12px; }
  .intro-right { text-align: left; padding-top: 0; }
  .intro-text { max-width: none; }
  .courses-grid { grid-template-columns: 1fr; }
  .timeline-item { grid-template-columns: 70px 1fr; }
}