/* ============================================
   Design Tokens
   ============================================ */
:root {
  --color-bg: #fafaf9;
  --color-surface: #ffffff;
  --color-border: #e7e5e4;
  --color-text: #1c1917;
  --color-text-secondary: #57534e;
  --color-text-muted: #a8a29e;
  --color-accent: #d97706;
  --color-accent-bg: #fef3c7;
  --color-accent-text: #92400e;
  --color-accent-border: #fde68a;

  --font-serif: Georgia, 'Times New Roman', serif;
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  --grid-gap: 12px;
  --card-padding: 20px;
  --card-radius: 12px;

  --duration-fast: 150ms;
  --duration-normal: 300ms;
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

/* ============================================
   Reset & Base
   ============================================ */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--duration-fast);
}

a:hover {
  color: var(--color-accent-text);
}

ul {
  list-style: none;
}

img {
  max-width: 100%;
  display: block;
}

/* ============================================
   Navigation
   ============================================ */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 24px;
  background: rgba(250, 250, 249, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.nav-logo {
  font-family: var(--font-serif);
  font-size: 1.125rem;
  color: var(--color-text);
  text-decoration: none;
}

.nav-logo:hover {
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  gap: 20px;
  align-items: center;
}

.nav-links a {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

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

.nav-cv {
  border: 1px solid var(--color-accent);
  padding: 4px 14px;
  border-radius: 6px;
  color: var(--color-accent) !important;
  font-weight: 500;
  transition: background var(--duration-fast), color var(--duration-fast);
}

.nav-cv:hover {
  background: var(--color-accent);
  color: var(--color-surface) !important;
}

/* ============================================
   Bento Grid
   ============================================ */
.bento {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--grid-gap);
  max-width: 1100px;
  margin: 24px auto;
  padding: 0 24px;
}

/* ============================================
   Card Base
   ============================================ */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--card-radius);
  padding: var(--card-padding);
  transition: transform var(--duration-normal) var(--ease-out),
              box-shadow var(--duration-normal) var(--ease-out);
}

.card-label {
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--color-accent);
  margin-bottom: 12px;
}

/* ============================================
   Bio Card
   ============================================ */
.card-bio {
  grid-column: span 2;
}

.card-bio h1 {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  font-weight: 400;
  line-height: 1.2;
}

.name-cn {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  filter: blur(5px);
  cursor: pointer;
  transition: filter var(--duration-normal) var(--ease-out);
  user-select: none;
}

.name-cn:hover {
  filter: blur(3px);
}

.name-cn.revealed {
  filter: blur(0);
  cursor: default;
}

.card-bio .subtitle {
  font-size: 0.875rem;
  color: var(--color-accent);
  margin-top: 4px;
  font-weight: 500;
}

.card-bio .subtitle a {
  color: inherit;
}

.bio-text {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  margin-top: 8px;
  line-height: 1.65;
}

.bio-text a {
  font-weight: 500;
}

.collab-link {
  text-decoration: underline;
  text-decoration-color: var(--color-border);
  text-underline-offset: 2px;
  color: var(--color-text-secondary);
  font-weight: 600;
}

.collab-link:hover {
  color: var(--color-accent);
  text-decoration-color: var(--color-accent);
}

.bio-cta {
  font-size: 0.8125rem;
  color: #1e40af;
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  padding: 6px 12px;
  border-radius: 6px;
  margin-top: 12px;
  line-height: 1.5;
}

.bio-cta a {
  color: #1d4ed8;
  font-weight: 600;
}

.bio-cta a:hover {
  color: #1e3a8a;
}

.tags {
  display: flex;
  gap: 6px;
  margin-top: 12px;
  flex-wrap: wrap;
}

.tag {
  font-size: 0.6875rem;
  background: var(--color-accent-bg);
  color: var(--color-accent-text);
  padding: 3px 10px;
  border-radius: 4px;
  font-weight: 500;
}

.social-links {
  display: flex;
  gap: 14px;
  margin-top: 12px;
}

.social-links a {
  font-size: 0.8125rem;
  color: var(--color-accent);
  font-weight: 500;
}

/* ============================================
   Education Card
   ============================================ */
.card-education {
  grid-column: span 1;
}

.edu-item {
  margin-bottom: 10px;
}

.edu-item:last-child {
  margin-bottom: 0;
}

.edu-degree {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text);
}

.edu-school {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

/* ============================================
   Education Detail
   ============================================ */
.edu-detail {
  font-size: 0.6875rem;
  color: var(--color-text-muted);
  margin-top: 1px;
}

.edu-detail a {
  color: var(--color-accent);
  font-weight: 500;
}

/* ============================================
   Photo Card (Carousel)
   ============================================ */
.card-photo {
  grid-column: span 1;
  padding: 0;
  overflow: hidden;
  position: relative;
}

.photo-carousel {
  position: relative;
  width: 100%;
  height: 100%;
  min-height: 180px;
}

.carousel-img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 15% center;
  opacity: 0;
  transition: opacity 0.5s ease;
}

.carousel-img.active {
  opacity: 1;
  position: relative;
}

.photo-dots {
  position: absolute;
  bottom: 10px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 6px;
  z-index: 2;
}

.dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.5);
  cursor: pointer;
  transition: background var(--duration-fast);
}

.dot.active {
  background: rgba(255, 255, 255, 0.95);
}

.dot:hover {
  background: rgba(255, 255, 255, 0.8);
}

/* Hide dots when only one photo */
.photo-dots:has(.dot:only-child) {
  display: none;
}

/* ============================================
   Papers Card
   ============================================ */
.card-papers {
  grid-column: span 2;
}

.papers-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.paper {
  padding-left: 10px;
  border-left: 2px solid var(--color-border);
}

.paper-first-author {
  border-left-color: var(--color-accent-border);
}

.paper-venue {
  font-size: 0.625rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.venue-highlight {
  color: var(--color-accent);
}

.paper-title {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.35;
  margin-top: 2px;
  transition: color var(--duration-fast);
}

.paper-title:hover {
  color: var(--color-accent);
}

.paper-authors {
  display: block;
  font-size: 0.6875rem;
  color: var(--color-text-muted);
  margin-top: 3px;
}

/* Paper Action Buttons */
.paper-actions {
  display: flex;
  gap: 5px;
  margin-top: 6px;
}

.paper-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.6rem;
  font-weight: 600;
  padding: 3px 9px;
  border-radius: 99px;
  cursor: pointer;
  text-decoration: none;
  line-height: 1.4;
  font-family: var(--font-sans);
  letter-spacing: 0.3px;
  text-transform: uppercase;
  border: none;
  transition: transform var(--duration-fast) var(--ease-out),
              box-shadow var(--duration-fast) var(--ease-out),
              background var(--duration-fast);
}

.paper-btn:hover {
  transform: translateY(-1px);
}

.paper-btn:active {
  transform: translateY(0);
}

.paper-btn-link {
  background: var(--color-accent);
  color: #fff;
  box-shadow: 0 1px 3px rgba(217, 119, 6, 0.25);
}

.paper-btn-link:hover {
  background: #b45309;
  color: #fff;
  box-shadow: 0 2px 8px rgba(217, 119, 6, 0.3);
}

.paper-btn-cite {
  background: var(--color-bg);
  color: var(--color-text-secondary);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
  border: 1px solid var(--color-border);
}

.paper-btn-cite:hover {
  background: var(--color-accent-bg);
  color: var(--color-accent-text);
  border-color: var(--color-accent-border);
  box-shadow: 0 2px 6px rgba(217, 119, 6, 0.12);
}

/* Cite Modal Overlay */
.cite-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 200;
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  align-items: center;
  justify-content: center;
}

.cite-overlay.active {
  display: flex;
}

.cite-modal {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--card-radius);
  padding: 20px;
  max-width: 560px;
  width: 90%;
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.12);
}

.cite-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.cite-label {
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--color-accent);
}

.cite-close {
  background: none;
  border: none;
  font-size: 1.25rem;
  color: var(--color-text-muted);
  cursor: pointer;
  line-height: 1;
  padding: 0 4px;
}

.cite-close:hover {
  color: var(--color-text);
}

.cite-content {
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 0.75rem;
  line-height: 1.6;
  color: var(--color-text-secondary);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 14px;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
}

.cite-copy {
  display: block;
  width: 100%;
  margin-top: 10px;
  padding: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  font-family: var(--font-sans);
  color: var(--color-accent);
  background: var(--color-accent-bg);
  border: 1px solid var(--color-accent-border);
  border-radius: 6px;
  cursor: pointer;
  transition: background var(--duration-fast), color var(--duration-fast);
}

.cite-copy:hover {
  background: var(--color-accent);
  color: var(--color-surface);
}

.cite-copy.copied {
  background: #d1fae5;
  color: #065f46;
  border-color: #6ee7b7;
}

.venue-review {
  color: var(--color-text-muted);
  font-style: italic;
}

.paper-under-review {
  opacity: 0.75;
}

.award-year {
  color: var(--color-text-muted);
  font-size: 0.75rem;
}

/* ============================================
   Awards Card
   ============================================ */
.card-awards {
  grid-column: span 1;
}

.awards-list li {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  line-height: 1.8;
}

.awards-list a {
  color: var(--color-text-secondary);
  text-decoration: underline;
  text-decoration-color: var(--color-border);
  text-underline-offset: 2px;
}

.awards-list a:hover {
  color: var(--color-accent);
  text-decoration-color: var(--color-accent);
}

/* ============================================
   Easter Egg Card
   ============================================ */
.card-easter-egg {
  grid-column: span 1;
  background: linear-gradient(135deg, var(--color-accent-bg), #fff7ed);
  border-color: var(--color-accent-border);
  cursor: pointer;
  position: relative;
  padding: 0;
  overflow: hidden;
}

.egg-front,
.egg-back {
  padding: var(--card-padding);
}

.egg-front {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  min-height: 100%;
}

.egg-icon {
  font-size: 2rem;
  margin-bottom: 8px;
}

.egg-title {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-accent-text);
}

.egg-hint {
  font-size: 0.75rem;
  color: #b45309;
  margin-top: 4px;
}

.egg-prompt {
  font-size: 0.6875rem;
  color: var(--color-accent);
  margin-top: 10px;
  opacity: 0.6;
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 0.4; }
  50% { opacity: 0.8; }
}

.egg-back {
  display: none;
}

.card-easter-egg.flipped .egg-front {
  display: none;
}

.card-easter-egg.flipped .egg-back {
  display: block;
}

.egg-content {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.egg-close {
  display: inline-block;
  margin-top: 12px;
  font-size: 0.75rem;
  color: var(--color-accent);
  cursor: pointer;
}

.egg-close:hover {
  color: var(--color-accent-text);
}

/* ============================================
   Service Card
   ============================================ */
.card-service {
  grid-column: span 2;
}

.service-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.service-subhead {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
}

.service-list li {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  line-height: 1.7;
}

/* ============================================
   Teaching Card
   ============================================ */
.card-teaching {
  grid-column: span 2;
}

.teaching-list li {
  margin-bottom: 6px;
}

.teaching-list li:last-child {
  margin-bottom: 0;
}

.teaching-course {
  display: block;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text);
}

.teaching-detail {
  display: block;
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

/* ============================================
   Footer
   ============================================ */
.footer {
  text-align: center;
  padding: 24px;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
  margin-top: 24px;
}

/* ============================================
   Hover Effects
   ============================================ */
.card-papers .paper:hover {
  transform: translateX(2px);
  transition: transform var(--duration-fast);
}

.card-easter-egg:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}

/* ============================================
   Responsive: Tablet (2 columns)
   ============================================ */
@media (max-width: 1023px) {
  .bento {
    grid-template-columns: repeat(2, 1fr);
  }

  .card-bio {
    grid-column: span 2;
  }

  .card-papers {
    grid-column: span 2;
  }

  .card-service {
    grid-column: span 2;
  }

  .card-teaching {
    grid-column: span 2;
  }
}

/* ============================================
   Responsive: Mobile (1 column)
   ============================================ */
@media (max-width: 767px) {
  .bento {
    grid-template-columns: 1fr;
    padding: 0 16px;
  }

  .card-bio,
  .card-papers,
  .card-service,
  .card-teaching {
    grid-column: span 1;
  }

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

  .service-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .nav {
    padding: 10px 16px;
  }

  .nav-links {
    gap: 12px;
  }

  .nav-links a {
    font-size: 0.8125rem;
  }

  .card-photo {
    max-height: 300px;
  }
}