/* ========================================
   RESET & BASE
   ======================================== */

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

:root {
  --black: #0a0a0a;
  --white: #fafafa;
  --gray-100: #f0f0f0;
  --gray-200: #e0e0e0;
  --gray-400: #999;
  --gray-600: #666;
  --gray-800: #333;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;
  --max-width: 860px;
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 2rem;
  --space-lg: 4rem;
  --space-xl: 6rem;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  color: var(--black);
  background: var(--white);
  line-height: 1.7;
  font-weight: 400;
}

a {
  color: inherit;
  text-decoration: none;
}

strong {
  font-weight: 600;
}

em {
  font-style: italic;
}

::selection {
  background: var(--black);
  color: var(--white);
}

/* ========================================
   NAV
   ======================================== */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(250, 250, 250, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--gray-200);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-name {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 1.1rem;
  letter-spacing: -0.02em;
}

.nav-links {
  display: flex;
  gap: var(--space-md);
}

.nav-links a {
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--gray-600);
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--black);
}

/* ========================================
   MAIN
   ======================================== */

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ========================================
   HERO
   ======================================== */

.hero {
  padding-top: calc(56px + var(--space-xl));
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid var(--gray-200);
}

.hero-content {
  display: flex;
  gap: var(--space-lg);
  align-items: flex-start;
}

.hero-photo {
  flex-shrink: 0;
  width: 160px;
  height: 160px;
  overflow: hidden;
  border: 1px solid var(--gray-200);
}

.hero-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: grayscale(20%);
  transition: filter 0.3s;
}

.hero-photo:hover img {
  filter: grayscale(0%);
}

.hero-text {
  flex: 1;
  min-width: 0;
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.1;
  margin-bottom: var(--space-xs);
}

.cursor-blink {
  font-family: var(--font-mono);
  font-weight: 300;
  animation: blink 1s step-end infinite;
}

@keyframes blink {
  50% { opacity: 0; }
}

.tagline {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--gray-600);
  letter-spacing: 0.02em;
  margin-bottom: var(--space-md);
}

.bio {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--gray-800);
  margin-bottom: var(--space-sm);
}

.hero-links {
  margin-top: var(--space-md);
  display: flex;
  gap: var(--space-sm);
}

.hero-links a {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 500;
  padding: 0.5rem 1.2rem;
  border: 1.5px solid var(--black);
  transition: all 0.2s;
}

.hero-links a:hover {
  background: var(--black);
  color: var(--white);
}

/* ========================================
   SECTIONS
   ======================================== */

.section {
  padding: var(--space-xl) 0;
  border-bottom: 1px solid var(--gray-200);
}

.section-header {
  display: flex;
  align-items: baseline;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
}

.section-number {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--gray-400);
  letter-spacing: 0.05em;
}

.section-header h2 {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.section-intro {
  font-size: 1rem;
  color: var(--gray-600);
  max-width: 600px;
  margin-bottom: var(--space-lg);
  line-height: 1.8;
}

/* ========================================
   RESEARCH CARDS
   ======================================== */

.research-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--gray-200);
  border: 1px solid var(--gray-200);
}

a.research-card {
  display: block;
  background: var(--white);
  padding: var(--space-md);
  transition: background 0.2s, padding-left 0.2s;
  cursor: pointer;
}

a.research-card:hover {
  background: var(--gray-100);
  padding-left: calc(var(--space-md) + 0.5rem);
}

.card-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-sm);
}

.card-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.2rem 0.6rem;
  border: 1px solid var(--black);
}

.card-year {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--gray-400);
}

.research-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.4;
  margin-bottom: 0.4rem;
}

.card-pillar {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--gray-600);
  letter-spacing: 0.03em;
  margin-bottom: var(--space-xs);
}

.card-authors {
  font-size: 0.82rem;
  color: var(--gray-400);
  margin-bottom: var(--space-xs);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--gray-200);
}

.research-card > p:last-child {
  font-size: 0.92rem;
  color: var(--gray-600);
  line-height: 1.7;
}

/* ========================================
   EDUCATION
   ======================================== */

.edu-list {
  display: flex;
  flex-direction: column;
}

.edu-item {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--gray-200);
}

.edu-item:first-child {
  border-top: 1px solid var(--gray-200);
}

.edu-period {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--gray-400);
  min-width: 130px;
  padding-top: 0.25rem;
  white-space: nowrap;
}

.edu-info h3 {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 0.2rem;
}

.edu-degree {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--gray-600);
  margin-bottom: 0.5rem;
}

.edu-info > p:last-child {
  font-size: 0.9rem;
  color: var(--gray-600);
  line-height: 1.7;
}

/* ========================================
   FOOTER
   ======================================== */

.footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-md);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--gray-400);
}

/* ========================================
   RESPONSIVE
   ======================================== */

@media (max-width: 640px) {
  :root {
    --space-xl: 3.5rem;
    --space-lg: 2.5rem;
  }

  .hero-content {
    flex-direction: column;
    gap: var(--space-md);
  }

  .hero-photo {
    width: 120px;
    height: 120px;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .nav-links {
    gap: var(--space-sm);
  }

  .nav-links a {
    font-size: 0.7rem;
  }

  .edu-item {
    flex-direction: column;
    gap: 0.25rem;
  }

  .edu-period {
    min-width: auto;
  }

  .hero-links {
    flex-wrap: wrap;
  }

  .section-header h2 {
    font-size: 1.4rem;
  }
}