/*
 * ============================================================
 *  style.css — Yong Chae Kim | Academic Personal Website
 *  Design: Bright, confident academic — high contrast,
 *          strong typography, visible cards and borders.
 *  Font: Source Serif 4 (headings) + DM Sans (body)
 * ============================================================
 */


/* ============================================================
   1. CSS CUSTOM PROPERTIES (DESIGN TOKENS)
   ============================================================ */

:root {
  /* --- Palette: Light Mode --- */
  --color-bg:           #ffffff;
  --color-bg-subtle:    #f6f8fb;
  --color-bg-inset:     #edf1f7;
  --color-surface:      #ffffff;
  --color-surface-hover:#f0f4ff;

  --color-border:       #d0d7e2;
  --color-border-strong:#a8b5c8;

  --color-text:         #111827;
  --color-text-muted:   #374151;
  --color-text-subtle:  #6b7280;
  --color-text-faint:   #9ca3af;

  --color-accent:       #1d4ed8;
  --color-accent-hover: #1e40af;
  --color-accent-subtle:#eff6ff;
  --color-accent-border:#93c5fd;

  --color-gold:         #92400e;
  --color-gold-bg:      #fef3c7;
  --color-gold-border:  #fcd34d;

  --color-silver:       #475569;
  --color-silver-bg:    #f1f5f9;
  --color-silver-border:#cbd5e1;

  --color-green:        #065f46;
  --color-green-bg:     #d1fae5;
  --color-green-border: #6ee7b7;

  /* --- Typography --- */
  --font-heading: 'Source Serif 4', 'Georgia', serif;
  --font-sans:    'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, sans-serif;
  --font-mono:    'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;

  /* --- Spacing --- */
  --nav-height:  62px;
  --page-max:    940px;
  --page-pad:    clamp(20px, 5vw, 48px);

  /* --- Radii --- */
  --radius-sm:   4px;
  --radius-md:   8px;
  --radius-lg:   12px;
  --radius-xl:   16px;
  --radius-pill: 100px;

  /* --- Shadows (stronger for visibility) --- */
  --shadow-sm:   0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
  --shadow-md:   0 4px 14px rgba(0, 0, 0, 0.12), 0 2px 6px rgba(0, 0, 0, 0.08);
  --shadow-lg:   0 12px 36px rgba(0, 0, 0, 0.14), 0 4px 10px rgba(0, 0, 0, 0.08);
  --shadow-hover:0 10px 30px rgba(29, 78, 216, 0.18), 0 4px 10px rgba(29, 78, 216, 0.10);

  /* --- Transitions --- */
  --ease:        cubic-bezier(0.4, 0, 0.2, 1);
  --transition:  0.2s var(--ease);
  --transition-slow: 0.3s var(--ease);
  --transition-theme: background-color 0.3s var(--ease),
                      color 0.3s var(--ease),
                      border-color 0.3s var(--ease),
                      box-shadow 0.3s var(--ease);
}


/* ============================================================
   2. CSS RESET & BASE
   ============================================================ */

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.75;
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: var(--transition-theme);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  max-width: 100%;
  display: block;
  -webkit-user-drag: none;
  user-select: none;
  pointer-events: none;
}

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

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

ul, ol {
  list-style: none;
}

button {
  cursor: pointer;
  font-family: inherit;
  border: none;
  background: none;
}

::selection {
  background: var(--color-accent-subtle);
  color: var(--color-accent);
}


/* ============================================================
   3. TYPOGRAPHY SCALE
   ============================================================ */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--color-text);
  transition: color var(--transition-slow);
}

h1 { font-size: clamp(2.25rem, 5vw, 3.25rem); font-weight: 800; letter-spacing: -0.02em; }
h2 { font-size: clamp(1.5rem, 3vw, 2rem);     font-weight: 700; }
h3 { font-size: clamp(1.125rem, 2vw, 1.375rem); font-weight: 600; }
h4 { font-size: 1rem;   font-weight: 600; }
h5 { font-size: 0.875rem; font-weight: 600; }
h6 { font-size: 0.8125rem; font-weight: 600; }

p {
  color: var(--color-text-muted);
  transition: color var(--transition-slow);
}

small {
  font-size: 0.8125rem;
  color: var(--color-text-subtle);
}

strong {
  font-weight: 600;
  color: var(--color-text);
}

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--color-bg-inset);
  padding: 0.15em 0.4em;
  border-radius: var(--radius-sm);
  color: var(--color-accent);
}


/* ============================================================
   4. NAVIGATION
   ============================================================ */

.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border-bottom: 1px solid var(--color-border);
  transition: var(--transition-theme),
              box-shadow var(--transition-slow);
}

.site-nav.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-inner {
  max-width: calc(var(--page-max) + var(--page-pad) * 2);
  margin: 0 auto;
  padding: 0 var(--page-pad);
  height: 100%;
  display: flex;
  align-items: center;
  gap: 16px;
}

/* Brand / logo */
.nav-brand {
  font-family: var(--font-heading);
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-text);
  white-space: nowrap;
  transition: color var(--transition-slow);
}

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

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

/* Desktop links */
.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}

.nav-links a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 6px 14px;
  border-radius: var(--radius-md);
  transition: color var(--transition), background var(--transition);
  position: relative;
}

.nav-links a:hover {
  color: var(--color-text);
  background: var(--color-bg-inset);
}

.nav-links a.active {
  color: var(--color-accent);
  font-weight: 600;
}

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 12px;
  right: 12px;
  height: 2.5px;
  background: var(--color-accent);
  border-radius: 2px 2px 0 0;
}

/* Theme toggle */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: var(--color-bg-inset);
  border: 1px solid var(--color-border);
  color: var(--color-text-subtle);
  transition: background var(--transition), border-color var(--transition),
              color var(--transition), transform var(--transition);
  flex-shrink: 0;
  font-size: 1.1rem;
}

.theme-toggle:hover {
  background: var(--color-bg-subtle);
  border-color: var(--color-border-strong);
  color: var(--color-text);
  transform: rotate(12deg);
}

.theme-toggle svg {
  width: 16px;
  height: 16px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.theme-toggle .icon-sun  { display: block; }
.theme-toggle .icon-moon { display: none; }

/* Language toggle */
.lang-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 36px;
  padding: 0 10px;
  border-radius: var(--radius-md);
  background: var(--color-bg-inset);
  border: 1px solid var(--color-border);
  color: var(--color-text-subtle);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-decoration: none;
  flex-shrink: 0;
  transition: background var(--transition), border-color var(--transition),
              color var(--transition);
}

.lang-toggle:hover {
  background: var(--color-bg-subtle);
  border-color: var(--color-border-strong);
  color: var(--color-text);
}

/* Hamburger -- mobile only */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: var(--color-bg-inset);
  color: var(--color-text-subtle);
  transition: background var(--transition), border-color var(--transition);
  padding: 8px;
  margin-left: 4px;
}

.hamburger:hover {
  background: var(--color-bg-subtle);
  border-color: var(--color-border-strong);
}

.hamburger span {
  display: block;
  width: 100%;
  height: 1.5px;
  background: currentColor;
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

.hamburger.open span:nth-child(1) { transform: rotate(45deg) translate(4.5px, 4.5px); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: rotate(-45deg) translate(4.5px, -4.5px); }

/* Mobile menu drawer */
.mobile-menu {
  display: none;
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: 8px 20px 16px;
  z-index: 999;
  flex-direction: column;
  gap: 2px;
  box-shadow: var(--shadow-md);
  transition: var(--transition-theme);
}

.mobile-menu.open {
  display: flex;
}

.mobile-menu a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 10px 14px;
  border-radius: var(--radius-md);
  transition: color var(--transition), background var(--transition);
}

.mobile-menu a:hover,
.mobile-menu a.active {
  color: var(--color-text);
  background: var(--color-bg-inset);
}

/* Mobile theme toggle inside menu — hidden on desktop */
.mobile-theme-toggle {
  display: none;
}

@media (max-width: 768px) {
  .mobile-theme-toggle {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-muted);
    padding: 10px 14px;
    border-radius: var(--radius-md);
    background: none;
    border: none;
    width: 100%;
    cursor: pointer;
    margin-top: 4px;
    border-top: 1px solid var(--color-border);
    padding-top: 14px;
    transition: color var(--transition), background var(--transition);
  }

  .mobile-theme-toggle:hover {
    color: var(--color-text);
    background: var(--color-bg-inset);
  }
}


/* ============================================================
   5. HERO / HOME PAGE
   ============================================================ */

.hero {
  padding-top: calc(var(--nav-height) + 72px);
  padding-bottom: 80px;
  padding-left: var(--page-pad);
  padding-right: var(--page-pad);
  max-width: calc(var(--page-max) + var(--page-pad) * 2);
  margin: 0 auto;
}

.hero-inner {
  display: flex;
  align-items: flex-start;
  gap: 56px;
}

/* Profile image */
.hero-image-wrap {
  flex-shrink: 0;
}

.hero-image {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  object-position: top center;
  border: 4px solid var(--color-border-strong);
  box-shadow: var(--shadow-lg);
  transition: border-color var(--transition-slow), box-shadow var(--transition-slow);
}

.hero-image:hover {
  border-color: var(--color-accent-border);
  box-shadow: var(--shadow-hover);
}

/* Text column */
.hero-content {
  flex: 1;
  min-width: 0;
}

.hero-name {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 4.5vw, 3rem);
  font-weight: 800;
  letter-spacing: -0.035em;
  line-height: 1.1;
  color: var(--color-text);
  margin-bottom: 8px;
  transition: color var(--transition-slow);
}

.hero-title {
  font-size: 1.0625rem;
  font-weight: 400;
  color: var(--color-text-subtle);
  margin-bottom: 20px;
  line-height: 1.5;
  transition: color var(--transition-slow);
}

.hero-title strong {
  color: var(--color-text-muted);
  font-weight: 500;
}

.hero-bio {
  font-size: 1rem;
  color: var(--color-text-muted);
  line-height: 1.8;
  margin-bottom: 12px;
  max-width: 640px;
  transition: color var(--transition-slow);
}

.hero-personal {
  font-size: 0.9375rem;
  color: var(--color-text-subtle);
  line-height: 1.7;
  margin-bottom: 28px;
  max-width: 600px;
  transition: color var(--transition-slow);
}

/* Social links */
.social-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-bottom: 32px;
}

.social-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-muted);
  padding: 7px 14px;
  border-radius: var(--radius-pill);
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  transition: color var(--transition), border-color var(--transition),
              background var(--transition), transform var(--transition),
              box-shadow var(--transition);
}

.social-link:hover {
  color: #ffffff;
  border-color: var(--color-accent);
  background: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.social-link svg {
  width: 14px;
  height: 14px;
  fill: currentColor;
  flex-shrink: 0;
}

/* Stats row */
.stats-row {
  display: flex;
  flex-wrap: wrap;
  gap: 32px;
  align-items: center;
  padding-top: 24px;
  border-top: 2px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

.stat-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.stat-num {
  font-family: var(--font-heading);
  font-size: 1.375rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--color-accent);
  transition: color var(--transition-slow);
}

.stat-label {
  font-size: 0.725rem;
  font-weight: 600;
  color: var(--color-text-subtle);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  transition: color var(--transition-slow);
}

.stat-divider {
  width: 1px;
  height: 36px;
  background: var(--color-border);
  transition: background var(--transition-slow);
}


/* ============================================================
   6. SECTION SHARED STYLES
   ============================================================ */

.page-main {
  padding-top: calc(var(--nav-height) + 48px);
  padding-bottom: 80px;
}

.page-container {
  max-width: calc(var(--page-max) + var(--page-pad) * 2);
  margin: 0 auto;
  padding-left: var(--page-pad);
  padding-right: var(--page-pad);
}

.section-header {
  margin-bottom: 40px;
}

.section-title {
  font-family: var(--font-heading);
  font-size: clamp(1.5rem, 2.5vw, 1.875rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 16px;
  transition: color var(--transition-slow);
}

.section-title::before {
  content: '';
  width: 4px;
  height: 28px;
  background: var(--color-accent);
  border-radius: 2px;
  flex-shrink: 0;
}

.section-title::after {
  content: '';
  flex: 1;
  height: 2px;
  background: linear-gradient(to right, var(--color-border), transparent);
  transition: background var(--transition-slow);
}

.section-subtitle {
  font-size: 1rem;
  color: var(--color-text-subtle);
  line-height: 1.7;
  max-width: 640px;
  transition: color var(--transition-slow);
}

/* Page title (top of each inner page) */
.page-title {
  margin-bottom: 48px;
  padding-bottom: 24px;
  border-bottom: 2px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

.page-title h1 {
  font-family: var(--font-heading);
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 800;
  letter-spacing: -0.035em;
  color: var(--color-text);
  margin-bottom: 8px;
  transition: color var(--transition-slow);
}

.page-title p {
  font-size: 1rem;
  color: var(--color-text-subtle);
  transition: color var(--transition-slow);
}

/* Research page header/subtitle */
.page-header {
  padding-top: calc(var(--nav-height) + 56px);
  padding-bottom: 32px;
  margin: 0 auto;
}

.page-header .page-title {
  font-family: var(--font-heading);
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 8px;
  padding-bottom: 0;
  border-bottom: none;
}

.page-header .page-subtitle {
  font-size: 1rem;
  color: var(--color-text-subtle);
  line-height: 1.7;
  max-width: 640px;
}

/* Research section container */
.research-section {
  padding-bottom: 80px;
  margin: 0 auto;
}

.container {
  max-width: var(--page-max);
  margin: 0 auto;
  padding-left: var(--page-pad);
  padding-right: var(--page-pad);
}


/* ============================================================
   7. CV PAGE
   ============================================================ */

/* CV Section blocks */
.cv-section {
  margin-bottom: 56px;
}

.cv-section + .cv-section {
  padding-top: 8px;
}

/* Timeline layout */
.timeline {
  position: relative;
  padding-left: 0;
}

.timeline-item {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 24px;
  padding: 20px 0;
  border-bottom: 1px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

.timeline-item:last-child {
  border-bottom: none;
}

.timeline-date {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-text-faint);
  padding-top: 3px;
  white-space: nowrap;
  transition: color var(--transition-slow);
}

.timeline-body {
  flex: 1;
  min-width: 0;
}

.timeline-title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 3px;
  transition: color var(--transition-slow);
}

.timeline-subtitle {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 4px;
  transition: color var(--transition-slow);
}

.timeline-detail {
  font-size: 0.8125rem;
  color: var(--color-text-subtle);
  transition: color var(--transition-slow);
}

/* Publication list */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.pub-item {
  display: grid;
  grid-template-columns: 38px 1fr;
  gap: 12px;
  padding: 14px 0;
  border-bottom: 1px solid var(--color-border);
  transition: border-color var(--transition-slow), background var(--transition);
}

.pub-item:last-child {
  border-bottom: none;
}

.pub-item:hover {
  background: var(--color-bg-subtle);
  border-radius: var(--radius-md);
}

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

.pub-id-col {
  padding-top: 2px;
}

.pub-id {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 38px;
  height: 26px;
  padding: 0 8px;
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.03em;
  color: #ffffff;
  background: var(--color-accent);
  border: none;
  border-radius: var(--radius-sm);
  transition: background var(--transition-slow), color var(--transition-slow);
}

.pub-content {
  min-width: 0;
}

.pub-title {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.45;
  margin-bottom: 4px;
  transition: color var(--transition);
}

.pub-title a {
  color: inherit;
  text-decoration: none;
}

.pub-title a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

.pub-authors {
  font-size: 0.8125rem;
  color: var(--color-text-subtle);
  line-height: 1.45;
  margin-bottom: 4px;
  transition: color var(--transition-slow);
}

.pub-authors .self {
  font-weight: 700;
  color: var(--color-text);
}

.pub-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  margin-top: 4px;
}

.pub-venue {
  font-size: 0.8125rem;
  font-style: italic;
  color: var(--color-text-muted);
  transition: color var(--transition-slow);
}

.pub-year {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-subtle);
  transition: color var(--transition-slow);
}

/* Impact Factor pill - GREEN and prominent */
.pub-if {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-green);
  background: var(--color-green-bg);
  border: 1.5px solid var(--color-green-border);
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  white-space: nowrap;
  transition: background var(--transition-slow), border-color var(--transition-slow),
              color var(--transition-slow);
}

.pill-if {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-green);
  background: var(--color-green-bg);
  border: 1.5px solid var(--color-green-border);
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  white-space: nowrap;
  transition: background var(--transition-slow), border-color var(--transition-slow),
              color var(--transition-slow);
}

.pill-if::before {
  content: 'IF';
  font-weight: 800;
}

/* Award badge on publication */
.pub-award,
.award-pill {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-gold);
  background: var(--color-gold-bg);
  border: 1.5px solid var(--color-gold-border);
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  white-space: nowrap;
  transition: background var(--transition-slow), border-color var(--transition-slow),
              color var(--transition-slow);
}

/* Index type pill (SCIE, ESCI) */
.pub-index,
.pill-index {
  display: inline-flex;
  align-items: center;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-accent);
  background: var(--color-accent-subtle);
  border: 1.5px solid var(--color-accent-border);
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  white-space: nowrap;
  transition: background var(--transition-slow), border-color var(--transition-slow),
              color var(--transition-slow);
}

/* Patent item */
.patent-item {
  display: grid;
  grid-template-columns: 36px 1fr;
  gap: 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

.patent-item:last-child {
  border-bottom: none;
}

.patent-id {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 30px;
  height: 22px;
  padding: 0 6px;
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--color-text-subtle);
  background: var(--color-bg-inset);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  transition: background var(--transition-slow), border-color var(--transition-slow),
              color var(--transition-slow);
}

.patent-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 3px;
  transition: color var(--transition-slow);
}

.patent-meta {
  font-size: 0.8125rem;
  color: var(--color-text-subtle);
  transition: color var(--transition-slow);
}

/* CV subsections */
.cv-subsection {
  margin-bottom: 28px;
}

.cv-subsection:last-child {
  margin-bottom: 0;
}

.subsection-title {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border);
  transition: color var(--transition-slow), border-color var(--transition-slow);
}

/* Reviewer list */
.reviewer-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.reviewer-item {
  font-size: 0.9375rem;
  color: var(--color-text);
  padding: 10px 0;
  border-bottom: 1px solid var(--color-border);
  transition: color var(--transition-slow), border-color var(--transition-slow);
}

.reviewer-item:last-child {
  border-bottom: none;
}

/* Reviewer tags (legacy) */
.reviewer-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.reviewer-tag {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--color-text-muted);
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  transition: background var(--transition), border-color var(--transition),
              color var(--transition), transform var(--transition);
}

.reviewer-tag:hover {
  background: var(--color-accent-subtle);
  border-color: var(--color-accent-border);
  color: var(--color-accent);
  transform: translateY(-1px);
}

/* Skills / tech tags */
.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 8px;
}

.skill-tag {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-subtle);
  background: var(--color-bg-inset);
  border: 1px solid var(--color-border);
  padding: 3px 10px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  transition: background var(--transition-slow), border-color var(--transition-slow),
              color var(--transition-slow);
}


/* ============================================================
   8. RESEARCH PAGE
   ============================================================ */

/* Filter tabs */
.filter-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 36px;
}

.filter-tab,
.filter-btn {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-muted);
  background: var(--color-bg);
  border: 1.5px solid var(--color-border);
  padding: 8px 18px;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: color var(--transition), background var(--transition),
              border-color var(--transition), transform var(--transition),
              box-shadow var(--transition);
}

.filter-tab:hover,
.filter-btn:hover {
  color: var(--color-text);
  background: var(--color-bg-inset);
  border-color: var(--color-border-strong);
}

.filter-tab.active,
.filter-btn.active {
  color: #ffffff;
  background: var(--color-accent);
  border-color: var(--color-accent);
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(29, 78, 216, 0.3);
}

/* Research grid */
.research-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

/* Research card */
.research-card {
  display: flex;
  flex-direction: column;
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: border-color var(--transition), box-shadow var(--transition),
              transform var(--transition), background var(--transition-slow);
}

.research-card:hover {
  border-color: var(--color-accent-border);
  box-shadow: var(--shadow-hover);
  transform: translateY(-4px);
}

.research-card.hidden {
  display: none;
}

/* Card image area -- 200px tall, cover fit */
.research-card-image {
  width: 100%;
  height: 200px;
  background: var(--color-bg);
  overflow: hidden;
  flex-shrink: 0;
  position: relative;
}

.research-card-image img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  transform-origin: center center;
}

.research-card:hover .research-card-image img {
  filter: brightness(1.03);
}

/* No-image placeholder gradient */
.research-card-image.no-image {
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #e0e7ff 0%, #dbeafe 40%, #f0f9ff 100%);
  border-bottom: 1.5px solid var(--color-border);
}

.research-card-image.no-image::after {
  content: '';
  width: 48px;
  height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%239ca3af' stroke-width='1.5'%3E%3Cpath d='M2.25 15.75l5.159-5.159a2.25 2.25 0 013.182 0l5.159 5.159m-1.5-1.5l1.409-1.409a2.25 2.25 0 013.182 0l2.909 2.909M3.75 21h16.5A2.25 2.25 0 0022.5 18.75V5.25A2.25 2.25 0 0020.25 3H3.75A2.25 2.25 0 001.5 5.25v13.5A2.25 2.25 0 003.75 21z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-size: contain;
  opacity: 0.35;
}

/* Placeholder for missing image (SVG icon version from index.html) */
.research-card-image.placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #e0e7ff 0%, #dbeafe 40%, #f0f9ff 100%);
  border-bottom: 1.5px solid var(--color-border);
}

.research-card-image.placeholder svg {
  width: 36px;
  height: 36px;
  color: var(--color-text-faint);
  opacity: 0.35;
}

/* Card body */
.research-card-body {
  padding: 20px 22px 22px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

/* Category pill on card */
.card-category,
.pill.category-first,
.pill.category-co,
.pill.category-ongoing,
.pill.category-project {
  display: inline-flex;
  align-items: center;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  align-self: flex-start;
  transition: background var(--transition-slow), color var(--transition-slow),
              border-color var(--transition-slow);
}

.card-category.first-author,
.pill.category-first {
  color: #ffffff;
  background: var(--color-accent);
  border: none;
}

.card-category.co-author,
.pill.category-co {
  color: var(--color-text-muted);
  background: var(--color-bg-inset);
  border: 1.5px solid var(--color-border-strong);
}

.card-category.ongoing,
.pill.category-ongoing {
  color: #ffffff;
  background: #059669;
  border: none;
}

.card-category.project,
.pill.category-project {
  color: #ffffff;
  background: #b45309;
  border: none;
}

.research-card-title {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.4;
  transition: color var(--transition-slow);
}

.research-card-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  line-height: 1.65;
  flex: 1;
  transition: color var(--transition-slow);
}

/* Card footer with ref and link */
.research-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-top: 8px;
  padding-top: 12px;
  border-top: 1px solid var(--color-border);
}

.research-card-ref {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-subtle);
}

/* Related paper link at bottom */
.research-card-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.8125rem;
  font-weight: 600;
  color: #ffffff;
  background: var(--color-accent);
  padding: 5px 14px;
  border-radius: var(--radius-pill);
  margin-top: 4px;
  transition: background var(--transition), transform var(--transition),
              box-shadow var(--transition);
  text-decoration: none;
}

.research-card-link:hover {
  background: var(--color-accent-hover);
  color: #ffffff;
  transform: translateY(-1px);
  box-shadow: 0 3px 10px rgba(29, 78, 216, 0.3);
}

.research-card-link svg {
  width: 13px;
  height: 13px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}


/* ============================================================
   9. AWARDS PAGE
   ============================================================ */

.awards-section {
  margin-bottom: 52px;
}

/* Award card */
.award-card {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 18px 0;
  border-bottom: 1px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

.award-card:last-child {
  border-bottom: none;
}

/* Left accent: colored vertical line */
.award-accent,
.award-card-accent {
  width: 4px;
  height: 100%;
  min-height: 40px;
  border-radius: 2px;
  flex-shrink: 0;
  align-self: stretch;
  transition: background var(--transition-slow);
}

.award-accent.gold,
.award-accent.silver,
.award-accent.bronze,
.award-accent.blue   { background: #94a3b8; }

/* Award card accent colors based on data-rank */
.award-card[data-rank="1st"] .award-card-accent,
.award-card[data-rank="2nd"] .award-card-accent,
.award-card[data-rank="top"] .award-card-accent,
.award-card[data-rank="other"] .award-card-accent { background: #94a3b8; }

.award-body,
.award-card-body {
  flex: 1;
  min-width: 0;
}

.award-title,
.award-card-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 3px;
  line-height: 1.4;
  transition: color var(--transition-slow);
}

.award-event,
.award-card-event {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 3px;
  transition: color var(--transition-slow);
}

.award-year,
.award-card-year {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-faint);
  transition: color var(--transition-slow);
}

/* Scholarship item — award-card style */
.scholarship-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 18px 0;
  border-bottom: 1px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

.scholarship-item:last-child {
  border-bottom: none;
}

.scholarship-accent {
  width: 4px;
  height: 36px;
  border-radius: 2px;
  flex-shrink: 0;
  margin-top: 2px;
  background: #94a3b8;
  transition: background var(--transition-slow);
}

[data-theme="dark"] .scholarship-accent {
  background: #64748b;
}

.scholarship-body {
  flex: 1;
  min-width: 0;
}

.scholarship-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 3px;
  line-height: 1.4;
  transition: color var(--transition-slow);
}

.scholarship-event {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 3px;
  transition: color var(--transition-slow);
}

.scholarship-meta {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-faint);
  transition: color var(--transition-slow);
}

/* Honor item — award-card style */
.honor-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 18px 0;
  border-bottom: 1px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

.honor-item:last-child {
  border-bottom: none;
}

.honor-accent {
  width: 4px;
  height: 36px;
  border-radius: 2px;
  flex-shrink: 0;
  margin-top: 2px;
  background: #94a3b8;
  transition: background var(--transition-slow);
}

[data-theme="dark"] .honor-accent {
  background: #64748b;
}

.honor-body {
  flex: 1;
  min-width: 0;
}

.honor-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 3px;
  line-height: 1.4;
  transition: color var(--transition-slow);
}

.honor-event {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 3px;
  transition: color var(--transition-slow);
}

.honor-meta {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-faint);
  transition: color var(--transition-slow);
}


/* ============================================================
   10. RESEARCH GRAPH (index.html)
   ============================================================ */

.research-graph-section {
  padding: 48px 0 56px;
}

.research-graph-wrap {
  width: 100%;
  max-width: 900px;
  margin: 0 auto;
  aspect-ratio: 900 / 520;
  position: relative;
}

.research-graph-wrap svg {
  width: 100%;
  height: 100%;
  display: block;
}

/* Graph edges */
.rg-edge {
  stroke: var(--color-border);
  stroke-width: 1.8;
  fill: none;
  opacity: 0.35;
  stroke-dasharray: 6 3;
  transition: stroke 0.3s, stroke-width 0.3s, opacity 0.3s, stroke-dasharray 0.3s;
}

.rg-edge.active {
  stroke-width: 2.5;
  opacity: 0.85;
  stroke-dasharray: none;
}

/* Graph circle nodes */
.rg-circle {
  transition: filter 0.3s, stroke-width 0.3s, transform 0.2s;
}

.rg-circle-center {
  filter: drop-shadow(0 3px 14px rgba(79,70,229,0.4));
}

.rg-circle-branch {
  opacity: 0.92;
  filter: drop-shadow(0 2px 8px rgba(0,0,0,0.15));
}

.rg-circle-leaf {
  filter: drop-shadow(0 1px 5px rgba(0,0,0,0.1));
  transition: filter 0.3s, stroke-width 0.3s, fill 0.3s;
}

/* Pulse animation for center */
.rg-pulse {
  animation: rgPulse 3.5s ease-in-out infinite;
}

@keyframes rgPulse {
  0%, 100% { r: 42; opacity: 0.35; }
  50% { r: 56; opacity: 0; }
}

/* Node group hover */
.rg-node-group {
  transition: opacity 0.2s;
}

.rg-node-group.hovered .rg-circle-leaf {
  stroke-width: 3;
  filter: drop-shadow(0 3px 12px rgba(0,0,0,0.22));
}

.rg-node-group.hovered .rg-circle-branch {
  filter: drop-shadow(0 4px 16px rgba(0,0,0,0.25));
  opacity: 1;
}

/* Labels */
.rg-label {
  font-family: 'DM Sans', sans-serif;
  font-size: 10.5px;
  font-weight: 800;
  text-anchor: middle;
  pointer-events: none;
  fill: var(--color-text);
  transition: fill 0.3s;
  letter-spacing: 0.01em;
}

.rg-label-center { fill: #fff; font-size: 14px; font-weight: 800; letter-spacing: 0.02em; }
.rg-label-branch { fill: #fff; font-size: 11px; font-weight: 700; }

.rg-sublabel {
  font-family: 'DM Sans', sans-serif;
  font-size: 8.5px;
  font-weight: 800;
  text-anchor: middle;
  pointer-events: none;
  fill: var(--color-text-secondary);
  transition: fill 0.3s;
}

.rg-sublabel-center { fill: rgba(255,255,255,0.8); font-size: 10.5px; font-weight: 800; }
.rg-sublabel-branch { fill: rgba(255,255,255,0.75); font-size: 9px; font-weight: 800; }

/* Tooltip */
.rg-tooltip {
  position: absolute;
  background: var(--color-bg-card, var(--color-bg));
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 14px 18px;
  font-size: 0.8125rem;
  line-height: 1.55;
  color: var(--color-text);
  max-width: 260px;
  box-shadow: 0 8px 30px rgba(0,0,0,0.14);
  pointer-events: none;
  opacity: 0;
  transform: translateY(8px) scale(0.96);
  transition: opacity 0.2s ease, transform 0.2s ease;
  z-index: 10;
  backdrop-filter: blur(8px);
}

.rg-tooltip.visible {
  opacity: 1;
  transform: translateY(0) scale(1);
}

.rg-tooltip-title {
  font-weight: 700;
  margin-bottom: 4px;
  color: var(--color-accent);
}

@media (max-width: 640px) {
  .research-graph-section { padding: 32px 0 40px; }
  .research-graph-wrap { aspect-ratio: 900 / 580; }
  .rg-label { font-size: 8.5px; }
  .rg-sublabel { font-size: 7px; }
  .rg-label-center { font-size: 11px; }
  .rg-label-branch { font-size: 9px; }
}


/* ============================================================
   11. CONTACT PAGE
   ============================================================ */

.contact-section {
  margin-bottom: 52px;
}

.contact-intro {
  font-size: 1rem;
  color: var(--color-text-muted);
  line-height: 1.8;
  max-width: 560px;
  margin-bottom: 36px;
  transition: color var(--transition-slow);
}

/* Prominent email */
.contact-email {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-text);
  padding: 14px 20px;
  background: var(--color-bg-subtle);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  margin-bottom: 48px;
  transition: color var(--transition), background var(--transition),
              border-color var(--transition), transform var(--transition),
              box-shadow var(--transition);
}

.contact-email:hover {
  color: var(--color-accent);
  background: var(--color-accent-subtle);
  border-color: var(--color-accent-border);
  transform: translateY(-1px);
  box-shadow: var(--shadow-hover);
}

.contact-email svg {
  width: 18px;
  height: 18px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex-shrink: 0;
  opacity: 0.6;
}

/* Contact grid of social cards */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 12px;
}

.contact-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px;
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  color: var(--color-text);
  transition: background var(--transition), border-color var(--transition),
              color var(--transition), transform var(--transition),
              box-shadow var(--transition);
}

.contact-card:hover {
  background: var(--color-accent-subtle);
  border-color: var(--color-accent-border);
  color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.contact-card-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: var(--color-bg-inset);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

.contact-card-icon svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

.contact-card-info {
  flex: 1;
  min-width: 0;
}

.contact-card-name {
  font-size: 0.875rem;
  font-weight: 600;
  color: inherit;
  display: block;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.contact-card-sub {
  font-size: 0.75rem;
  color: var(--color-text-faint);
  display: block;
  transition: color var(--transition-slow);
}

.contact-card-arrow {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  opacity: 0.4;
  flex-shrink: 0;
  transition: opacity var(--transition), transform var(--transition);
}

.contact-card:hover .contact-card-arrow {
  opacity: 0.8;
  transform: translateX(2px);
}


/* ============================================================
   11. SHARED COMPONENTS
   ============================================================ */

/* Generic card */
.card {
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: background var(--transition-slow), border-color var(--transition),
              box-shadow var(--transition), transform var(--transition);
}

.card:hover {
  border-color: var(--color-border-strong);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.card-pad {
  padding: 24px;
}

/* Badge / pill base */
.badge {
  display: inline-flex;
  align-items: center;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  transition: background var(--transition-slow), color var(--transition-slow),
              border-color var(--transition-slow);
}

.badge-accent {
  color: var(--color-accent);
  background: var(--color-accent-subtle);
  border-color: var(--color-accent-border);
}

.badge-gold {
  color: var(--color-gold);
  background: var(--color-gold-bg);
  border-color: var(--color-gold-border);
}

.badge-subtle {
  color: var(--color-text-subtle);
  background: var(--color-bg-inset);
  border-color: var(--color-border);
}

.pill {
  display: inline-flex;
  align-items: center;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  border: 1px solid var(--color-border);
  background: var(--color-bg-subtle);
  color: var(--color-text-muted);
  transition: background var(--transition-slow), color var(--transition-slow),
              border-color var(--transition-slow);
}

/* Divider */
.divider {
  height: 1px;
  background: var(--color-border);
  margin: 40px 0;
  transition: background var(--transition-slow);
}

/* Button: primary */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  padding: 10px 24px;
  border-radius: var(--radius-pill);
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: background var(--transition), color var(--transition),
              border-color var(--transition), transform var(--transition),
              box-shadow var(--transition);
  text-decoration: none;
}

.btn-primary {
  color: #ffffff;
  background: var(--color-accent);
  border-color: var(--color-accent);
}

.btn-primary:hover {
  color: #ffffff;
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(29, 78, 216, 0.3);
}

.btn-outline {
  color: var(--color-accent);
  background: var(--color-accent-subtle);
  border-color: var(--color-accent-border);
}

.btn-outline:hover {
  color: #ffffff;
  background: var(--color-accent);
  border-color: var(--color-accent);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(29, 78, 216, 0.25);
}


/* ============================================================
   12. FOOTER
   ============================================================ */

.site-footer {
  padding: 32px var(--page-pad);
  border-top: 2px solid var(--color-border);
  text-align: center;
  transition: border-color var(--transition-slow);
}

.site-footer p {
  font-size: 0.8125rem;
  color: var(--color-text-subtle);
  line-height: 1.6;
  transition: color var(--transition-slow);
}

.site-footer a {
  color: var(--color-accent);
  font-weight: 600;
  transition: color var(--transition);
}

.site-footer a:hover {
  color: var(--color-accent-hover);
}


/* ============================================================
   13. ANIMATIONS & TRANSITIONS
   ============================================================ */

/* Fade-in on scroll */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s var(--ease), transform 0.6s var(--ease);
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered delay helpers */
.delay-1 { transition-delay: 0.08s; }
.delay-2 { transition-delay: 0.16s; }
.delay-3 { transition-delay: 0.24s; }
.delay-4 { transition-delay: 0.32s; }
.delay-5 { transition-delay: 0.40s; }

/* Subtle background animation for hero */
@keyframes fadeSlideUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

.hero-content > * {
  animation: fadeSlideUp 0.7s var(--ease) both;
}

.hero-content > *:nth-child(1) { animation-delay: 0.05s; }
.hero-content > *:nth-child(2) { animation-delay: 0.12s; }
.hero-content > *:nth-child(3) { animation-delay: 0.19s; }
.hero-content > *:nth-child(4) { animation-delay: 0.26s; }
.hero-content > *:nth-child(5) { animation-delay: 0.33s; }
.hero-content > *:nth-child(6) { animation-delay: 0.40s; }

.hero-image-wrap {
  animation: fadeSlideUp 0.7s var(--ease) 0.08s both;
}

/* Respect reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  .fade-in { opacity: 1; transform: none; }
}


/* ============================================================
   14. RESPONSIVE BREAKPOINTS
   ============================================================ */

/* ---- Tablet: 768px - 1024px ---- */
@media (max-width: 1024px) {
  .research-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
  }

  .timeline-item {
    grid-template-columns: 120px 1fr;
    gap: 16px;
  }
}

/* ---- Mobile: < 768px ---- */
@media (max-width: 768px) {
  :root {
    --nav-height: 56px;
  }

  /* Nav: hide desktop links, show hamburger */
  .nav-links {
    display: none;
  }

  .nav-links {
    display: none;
  }

  .theme-toggle {
    display: none;
  }

  .lang-toggle {
    margin-left: auto;
    width: 36px;
    height: 36px;
    padding: 0;
    border-radius: var(--radius-md);
  }

  .hamburger {
    display: flex;
  }

  /* Hero: stack vertically, photo on top */
  .hero {
    padding-top: calc(var(--nav-height) + 32px);
    padding-bottom: 48px;
  }

  .hero-inner {
    flex-direction: column;
    gap: 24px;
    align-items: center;
    text-align: center;
  }

  .hero-image {
    width: 130px;
    height: 130px;
  }

  .hero-name {
    font-size: 1.75rem;
  }

  .hero-bio,
  .hero-personal {
    text-align: left;
  }

  .social-links {
    justify-content: center;
  }

  .stats-row {
    justify-content: center;
  }

  /* Timeline: collapse columns */
  .timeline-item {
    display: block;
    padding: 16px 0;
  }

  .timeline-date {
    display: block;
    margin-bottom: 6px;
  }

  /* Pub items */
  .pub-item,
  .patent-item {
    grid-template-columns: 36px 1fr;
    gap: 10px;
  }

  /* Research: single column */
  .research-grid {
    grid-template-columns: 1fr;
  }

  /* Research card image shorter on mobile */
  .research-card-image {
    height: 160px;
  }

  /* Contact grid */
  .contact-grid {
    grid-template-columns: 1fr 1fr;
  }

  /* Stats row on mobile: keep flex with dividers */
  .stats-row {
    gap: 16px 24px;
    flex-wrap: wrap;
    justify-content: center;
  }

  .stat-divider {
    height: 28px;
  }

  /* Contact links: 2-column on tablet */
  .contact-links-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  /* Filter tabs: scrollable row */
  .filter-tabs {
    flex-wrap: nowrap;
    overflow-x: auto;
    padding-bottom: 4px;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }

  .filter-tabs::-webkit-scrollbar {
    display: none;
  }

  .filter-tab,
  .filter-btn {
    flex-shrink: 0;
  }
}

/* ---- Small mobile: < 480px ---- */
@media (max-width: 480px) {
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .social-links {
    flex-wrap: wrap;
    gap: 6px;
  }

  .social-link {
    font-size: 0.8rem;
    padding: 6px 10px;
  }

  .hero-image {
    width: 110px;
    height: 110px;
  }

  .hero-name {
    font-size: 1.5rem;
  }

  .hero-title {
    font-size: 0.9375rem;
  }

  .hero-bio,
  .hero-personal {
    font-size: 0.875rem;
  }

  .stats-row {
    gap: 12px 18px;
  }

  .stat-num {
    font-size: 1.125rem;
  }

  .stat-label {
    font-size: 0.625rem;
  }

  .stat-divider {
    height: 24px;
  }

  .research-card-image {
    height: 140px;
  }

  /* Contact links: single column on small */
  .contact-links-grid {
    grid-template-columns: 1fr;
  }

  .page-title {
    font-size: 1.5rem;
  }

  .section-title {
    font-size: 1.125rem;
  }
}


/* ============================================================
   15. DARK MODE -- [data-theme="dark"]
   ============================================================ */

[data-theme="dark"] {
  /* Backgrounds */
  --color-bg:           #0f172a;
  --color-bg-subtle:    #1e293b;
  --color-bg-inset:     #0f172a;
  --color-surface:      #1e293b;
  --color-surface-hover:#233354;

  /* Borders */
  --color-border:       #334155;
  --color-border-strong:#475569;

  /* Text */
  --color-text:         #f1f5f9;
  --color-text-muted:   #cbd5e1;
  --color-text-subtle:  #94a3b8;
  --color-text-faint:   #64748b;

  /* Accent */
  --color-accent:       #60a5fa;
  --color-accent-hover: #93c5fd;
  --color-accent-subtle:#1e3a5f;
  --color-accent-border:#1d4ed8;

  /* Gold */
  --color-gold:         #fbbf24;
  --color-gold-bg:      #1c1408;
  --color-gold-border:  #78350f;

  /* Silver */
  --color-silver:       #94a3b8;
  --color-silver-bg:    #1e293b;
  --color-silver-border:#334155;

  /* Green */
  --color-green:        #34d399;
  --color-green-bg:     #022c22;
  --color-green-border: #064e3b;

  /* Shadows (more opaque on dark) */
  --shadow-sm:   0 1px 3px rgba(0, 0, 0, 0.4),  0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md:   0 4px 12px rgba(0, 0, 0, 0.5),  0 2px 4px rgba(0, 0, 0, 0.4);
  --shadow-lg:   0 12px 32px rgba(0, 0, 0, 0.6), 0 4px 8px rgba(0, 0, 0, 0.4);
  --shadow-hover:0 8px 24px rgba(96, 165, 250, 0.15), 0 2px 6px rgba(96, 165, 250, 0.08);
}

/* Dark mode nav */
[data-theme="dark"] .site-nav {
  background: rgba(15, 23, 42, 0.95);
  border-bottom-color: var(--color-border);
}

[data-theme="dark"] .mobile-menu {
  background: #0f172a;
  border-bottom-color: var(--color-border);
}

/* Dark mode: flip theme toggle icons */
[data-theme="dark"] .theme-toggle .icon-sun  { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: block; }

/* Dark mode: hero image border */
[data-theme="dark"] .hero-image {
  border-color: var(--color-border-strong);
}

/* Dark mode: contact email */
[data-theme="dark"] .contact-email {
  background: var(--color-bg-subtle);
  border-color: var(--color-border-strong);
}

/* Dark mode: research card no-image / placeholder */
[data-theme="dark"] .research-card-image.no-image,
[data-theme="dark"] .research-card-image.placeholder {
  background: linear-gradient(135deg, #1e293b 0%, #1e3a5f 100%);
  border-bottom-color: var(--color-border);
}

/* Dark mode: pub-id badge */
[data-theme="dark"] .pub-id {
  background: var(--color-accent);
  color: #0f172a;
}

/* Dark mode: category pills */
[data-theme="dark"] .pill.category-first {
  background: var(--color-accent);
  color: #0f172a;
}

[data-theme="dark"] .pill.category-ongoing {
  background: #059669;
  color: #ffffff;
}

[data-theme="dark"] .pill.category-project {
  background: #d97706;
  color: #0f172a;
}

/* Dark mode: filter buttons active */
[data-theme="dark"] .filter-tab.active,
[data-theme="dark"] .filter-btn.active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: #0f172a;
}

/* Dark mode: social link hover */
[data-theme="dark"] .social-link:hover {
  color: #0f172a;
  background: var(--color-accent);
  border-color: var(--color-accent);
}

/* Dark mode: btn-outline */
[data-theme="dark"] .btn-outline {
  color: var(--color-accent);
  background: var(--color-accent-subtle);
  border-color: var(--color-accent-border);
}

[data-theme="dark"] .btn-outline:hover {
  color: #0f172a;
  background: var(--color-accent);
  border-color: var(--color-accent);
}

/* Dark mode: btn-primary */
[data-theme="dark"] .btn-primary {
  color: #0f172a;
}

/* Dark mode: research card link */
[data-theme="dark"] .research-card-link {
  background: var(--color-accent);
  color: #0f172a;
}

/* Dark mode: award accent overrides */
[data-theme="dark"] .award-accent.gold,
[data-theme="dark"] .award-accent.silver,
[data-theme="dark"] .award-accent.blue   { background: #64748b; }
[data-theme="dark"] .award-card[data-rank="1st"] .award-card-accent,
[data-theme="dark"] .award-card[data-rank="2nd"] .award-card-accent,
[data-theme="dark"] .award-card[data-rank="top"] .award-card-accent,
[data-theme="dark"] .award-card[data-rank="other"] .award-card-accent { background: #64748b; }

/* Dark mode: no-image placeholder icon */
[data-theme="dark"] .research-card-image.no-image::after {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='1.5'%3E%3Cpath d='M2.25 15.75l5.159-5.159a2.25 2.25 0 013.182 0l5.159 5.159m-1.5-1.5l1.409-1.409a2.25 2.25 0 013.182 0l2.909 2.909M3.75 21h16.5A2.25 2.25 0 0022.5 18.75V5.25A2.25 2.25 0 0020.25 3H3.75A2.25 2.25 0 001.5 5.25v13.5A2.25 2.25 0 003.75 21z'/%3E%3C/svg%3E");
}

/* ============================================================
   CONTACT PAGE (redesigned)
   ============================================================ */

.contact-email-block {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 24px 28px;
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: 12px;
}

.contact-links-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 20px;
}

.contact-link-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 28px 20px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  text-decoration: none;
  color: var(--color-text);
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.2s;
}
.contact-link-card:hover {
  border-color: var(--color-accent);
  box-shadow: 0 4px 16px rgba(37, 99, 235, 0.1);
  transform: translateY(-2px);
}
.contact-link-card svg {
  width: 32px;
  height: 32px;
  color: var(--color-text-secondary);
  transition: color 0.2s;
}
.contact-link-card:hover svg {
  color: var(--color-accent);
}
.contact-link-name {
  font-size: 15px;
  font-weight: 700;
}
.contact-link-sub {
  font-size: 13px;
  color: var(--color-text-secondary);
}

@media (max-width: 768px) {
  .contact-links-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (max-width: 480px) {
  .contact-links-grid {
    grid-template-columns: 1fr;
  }
}


/* ============================================================
   Citation Chart
   ============================================================ */
.citation-section {
  padding-bottom: 16px;
}

.citation-chart-wrap {
  background: var(--color-bg-card, var(--color-bg));
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 36px 32px 28px;
  transition: border-color var(--transition-slow), background var(--transition-slow);
}

.citation-stats {
  display: flex;
  justify-content: center;
  gap: 0;
  margin-bottom: 36px;
}

.citation-stat {
  text-align: center;
  padding: 0 36px;
  position: relative;
}

.citation-stat + .citation-stat::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 1px;
  height: 36px;
  background: var(--color-border);
}

.citation-stat-num {
  display: block;
  font-family: var(--font-heading);
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--color-accent);
  line-height: 1.2;
}

.citation-stat-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-text-subtle);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-top: 2px;
}

.citation-chart-area {
  position: relative;
  padding-left: 40px;
}

.citation-grid-lines {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 30px;
  pointer-events: none;
}

.citation-grid-line {
  position: absolute;
  left: 40px;
  right: 0;
  height: 1px;
  background: var(--color-border);
  opacity: 0.45;
}

.citation-grid-label {
  position: absolute;
  left: 0;
  transform: translateY(50%);
  font-size: 0.625rem;
  font-weight: 600;
  color: var(--color-text-subtle);
  opacity: 0.6;
  width: 34px;
  text-align: right;
  line-height: 1;
}

.citation-chart {
  display: flex;
  align-items: flex-end;
  justify-content: center;
  gap: 8px;
  height: 200px;
  padding: 0;
  position: relative;
  z-index: 1;
}

.citation-bar-group {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex: 1;
  max-width: 72px;
  cursor: pointer;
}

.citation-bar-count {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: 6px;
  opacity: 0;
  transform: translateY(6px);
  transition: opacity 0.4s, transform 0.4s;
}

.citation-bar.animate ~ .citation-bar-year,
.citation-bar-count.show {
  opacity: 1;
  transform: translateY(0);
}

.citation-bar-group:hover .citation-bar-count {
  opacity: 1;
  transform: translateY(0);
}

.citation-bar {
  width: 100%;
  background: linear-gradient(180deg, var(--color-accent), color-mix(in srgb, var(--color-accent) 65%, transparent));
  border-radius: 6px 6px 0 0;
  min-height: 4px;
  transform-origin: bottom;
  transform: scaleY(0);
  transition: transform 0.7s cubic-bezier(0.34, 1.56, 0.64, 1), filter 0.3s;
  position: relative;
}

.citation-bar-group:hover .citation-bar {
  filter: brightness(1.2);
}

.citation-bar.animate {
  transform: scaleY(1);
}

.citation-bar-year {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-text-subtle);
  margin-top: 10px;
}

.citation-bar-group:hover .citation-bar-year {
  color: var(--color-text);
}

.citation-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--color-border);
}

.citation-source {
  font-size: 0.75rem;
  color: var(--color-text-subtle);
  opacity: 0.7;
  margin: 0;
}

.citation-source a {
  color: var(--color-accent);
  text-decoration: none;
  font-weight: 600;
}

.citation-source a:hover {
  text-decoration: underline;
}

.citation-updated {
  font-size: 0.6875rem;
  color: var(--color-text-subtle);
  opacity: 0.5;
}

@media (max-width: 768px) {
  .citation-stats {
    gap: 0;
  }
  .citation-stat {
    padding: 0 20px;
  }
  .citation-stat + .citation-stat::before {
    height: 28px;
  }
  .citation-stat-num {
    font-size: 1.5rem;
  }
  .citation-chart {
    height: 160px;
    gap: 5px;
  }
  .citation-chart-wrap {
    padding: 24px 16px 20px;
  }
  .citation-chart-area {
    padding-left: 32px;
  }
  .citation-grid-lines {
    bottom: 30px;
  }
  .citation-grid-line {
    left: 32px;
  }
  .citation-grid-label {
    width: 26px;
    font-size: 0.5625rem;
  }
  .citation-footer {
    flex-direction: column;
    gap: 4px;
    align-items: flex-start;
  }
}

/* ============================================================
   END OF style.css
   ============================================================ */