:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f7f7f8;
  --color-bg-card: #ffffff;
  --color-surface: #f0f0f2;
  --color-text: #1a1a2e;
  --color-text-muted: #555566;
  --color-text-subtle: #8a8a9a;
  --color-accent: #2d5de0;
  --color-accent-hover: #1a47c2;
  --color-border: #e2e2e8;
  --font-serif: Georgia, 'Times New Roman', 'Noto Serif', serif;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --max-width: 1100px;
  --nav-height: 64px;
  --section-padding: 120px;
  --transition: 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background var(--transition);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 500;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: 0.01em;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 32px;
}

.nav-link {
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--color-text-muted);
  text-decoration: none;
  letter-spacing: 0.03em;
  transition: color var(--transition);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--color-accent);
  transition: width var(--transition);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-text);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  z-index: 1001;
}

.hamburger-line {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--color-text);
  transition: all var(--transition);
}

.hamburger.active .hamburger-line:nth-child(1) {
  transform: rotate(45deg) translate(4px, 5px);
}

.hamburger.active .hamburger-line:nth-child(2) {
  opacity: 0;
}

.hamburger.active .hamburger-line:nth-child(3) {
  transform: rotate(-45deg) translate(4px, -5px);
}

/* Focus styles */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.nav-link:focus-visible::after {
  width: 100%;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}

/* Sections */
.section {
  padding: var(--section-padding) 0;
}

.section-title {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 16px;
  letter-spacing: -0.01em;
}

.section-subtitle {
  font-size: 1rem;
  color: var(--color-text-muted);
  margin-bottom: 56px;
  max-width: 640px;
  line-height: 1.7;
}

.section-subtitle a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition);
}

.section-subtitle a:hover {
  color: var(--color-accent-hover);
}

/* About / Hero */
.section-about {
  padding-top: calc(var(--nav-height) + 100px);
  padding-bottom: var(--section-padding);
  min-height: 100vh;
  display: flex;
  align-items: center;
}

.about-hero {
  max-width: 700px;
}

.about-name {
  font-family: var(--font-serif);
  font-size: clamp(2.6rem, 5.5vw, 3.8rem);
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.1;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.about-tagline {
  font-size: 1rem;
  color: var(--color-text-subtle);
  margin-bottom: 48px;
  line-height: 1.5;
  font-weight: 400;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.about-intro-block {
  border-left: 2px solid var(--color-border);
  padding-left: 24px;
  margin-bottom: 8px;
}

.about-intro {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  margin-bottom: 16px;
  line-height: 1.75;
  max-width: 620px;
}

.about-intro:last-child {
  margin-bottom: 0;
}

.about-cta {
  display: flex;
  gap: 16px;
  margin-top: 44px;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 9px 24px;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 500;
  text-decoration: none;
  border-radius: 6px;
  transition: all var(--transition);
  letter-spacing: 0.02em;
  cursor: pointer;
  border: 1px solid transparent;
}

.btn-primary {
  background: #4a90d9;
  color: #ffffff;
  border-color: #4a90d9;
}

.btn-primary:hover {
  background: #3a7bc8;
  border-color: #3a7bc8;
}

.btn-secondary {
  background: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}

.btn-secondary:hover {
  border-color: var(--color-text-muted);
  color: var(--color-text);
}

/* Card Grid */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}

.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 32px;
  transition: all var(--transition);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

.card:hover {
  border-color: var(--color-text-subtle);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.card-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 16px;
}

.card-title {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 12px;
  line-height: 1.4;
}

.card-text {
  font-size: 0.925rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: 16px;
}

.card-link {
  font-size: 0.875rem;
  color: var(--color-accent);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition);
}

.card-link:hover {
  color: var(--color-accent-hover);
}

/* Coming Soon Note */
.coming-soon-note {
  font-size: 0.875rem;
  color: var(--color-text-subtle);
  font-style: italic;
  margin-bottom: 32px;
  padding: 12px 16px;
  border-left: 2px solid var(--color-border);
  background: var(--color-bg-alt);
  border-radius: 0 6px 6px 0;
}

/* Teaching */
.section-intro {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  max-width: 700px;
  line-height: 1.8;
  margin-bottom: 56px;
}

.teaching-entries {
  display: flex;
  flex-direction: column;
}

.teaching-entry {
  display: flex;
  gap: 40px;
  padding: 32px 0;
  border-top: 1px solid var(--color-border);
}

.teaching-entry:last-child {
  border-bottom: 1px solid var(--color-border);
}

.teaching-entry-year {
  flex-shrink: 0;
  width: 64px;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text-subtle);
  padding-top: 4px;
}

.teaching-entry-content {
  flex: 1;
}

.teaching-entry-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.4;
  margin-bottom: 10px;
}

.teaching-entry-desc {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: 12px;
}

/* Contact */
.section-contact {
  text-align: center;
}

.contact-text {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  max-width: 560px;
  margin: 0 auto 36px;
  line-height: 1.8;
}

.contact-links-inline {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 28px;
}

.contact-links-inline a {
  font-size: 0.9rem;
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition);
}

.contact-links-inline a:hover {
  color: var(--color-accent);
}

/* Footer */
.footer {
  border-top: 1px solid var(--color-border);
  padding: 48px 0 40px;
}

.footer-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-copy {
  font-size: 0.8rem;
  color: var(--color-text-subtle);
}

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

.footer-links a {
  font-size: 0.8rem;
  color: var(--color-text-subtle);
  text-decoration: none;
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--color-text);
}

/* Responsive */
@media (max-width: 768px) {
  :root {
    --section-padding: 80px;
  }

  .hamburger {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100vh;
    background: var(--color-bg);
    flex-direction: column;
    padding: 100px 40px 40px;
    gap: 24px;
    transition: right var(--transition);
    border-left: 1px solid var(--color-border);
    box-shadow: -4px 0 20px rgba(0, 0, 0, 0.08);
  }

  .nav-menu.open {
    right: 0;
  }

  .nav-link {
    font-size: 1rem;
  }

  .section-about {
    padding-top: calc(var(--nav-height) + 60px);
    min-height: auto;
  }

  .about-name {
    font-size: 2.4rem;
  }

  .about-tagline {
    font-size: 1.05rem;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .teaching-entry {
    flex-direction: column;
    gap: 8px;
  }

  .teaching-entry-year {
    width: auto;
  }

  .footer-container {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  .about-cta {
    flex-direction: column;
  }

  .btn {
    text-align: center;
  }
}