/* ============================================
   ICON Lab Website - Design System
   Style reference: yongchae.com
   ============================================ */

/* 1. CSS Custom Properties */
:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f6f8fb;
  --color-bg-card: #edf1f7;
  --color-text: #111827;
  --color-text-muted: #374151;
  --color-text-subtle: #6b7280;
  --color-accent: #1d4ed8;
  --color-accent-hover: #1e40af;
  --color-accent-light: #dbeafe;
  --color-border: #e5e7eb;
  --color-border-light: #f3f4f6;
  --font-heading: 'Source Serif 4', Georgia, serif;
  --font-body: 'DM Sans', 'Pretendard', system-ui, -apple-system, sans-serif;
  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;
  --max-width: 1200px;
  --nav-height: 62px;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-pill: 100px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 36px rgba(0,0,0,0.1);
  --shadow-hover: 0 8px 24px rgba(29,78,216,0.12);
  --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-bg-alt: #1e293b;
  --color-bg-card: #1e293b;
  --color-text: #f1f5f9;
  --color-text-muted: #cbd5e1;
  --color-text-subtle: #94a3b8;
  --color-accent: #60a5fa;
  --color-accent-hover: #93c5fd;
  --color-accent-light: #1e3a5f;
  --color-border: #334155;
  --color-border-light: #1e293b;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
  --shadow-lg: 0 12px 36px rgba(0,0,0,0.4);
  --shadow-hover: 0 8px 24px rgba(96,165,250,0.15);
}

/* 2. Reset & Base */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

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

body {
  font-family: var(--font-body);
  font-size: 18px;
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
  transition: background var(--transition-slow), color var(--transition-slow);
  -webkit-font-smoothing: antialiased;
}

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

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

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.2;
  color: var(--color-text);
}

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; margin-bottom: 0.5rem; }
h4 { font-size: 1rem; font-weight: 600; }

p { margin-bottom: 1rem; color: var(--color-text-muted); }

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

/* 3. Layout */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 48px);
}

.section {
  padding: clamp(48px, 8vw, 80px) 0;
}

.section-alt {
  background: var(--color-bg-alt);
}

.section-title {
  margin-bottom: clamp(24px, 4vw, 32px);
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: clamp(1.5rem, 2.5vw, 1.875rem);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.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);
}

/* 4. Navigation */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 48px);
  height: 100%;
  display: flex;
  align-items: center;
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}

.nav-brand {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: 8px;
}

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

.nav-brand .brand-icon {
  width: 32px;
  height: 32px;
  background: var(--color-accent);
  color: white;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.875rem;
  font-weight: 800;
  font-family: var(--font-body);
}

.nav-brand .brand-logo-univ {
  height: 32px;
  width: auto;
  margin-left: 12px;
}

.nav-brand .brand-logo {
  height: 36px;
  width: auto;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.nav-links a {
  padding: 6px 14px;
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-muted);
  transition: all var(--transition);
  letter-spacing: -0.01em;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-accent);
  background: var(--color-accent-light);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-btn {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 6px 10px;
  cursor: pointer;
  color: var(--color-text-muted);
  font-size: 0.8rem;
  font-weight: 600;
  font-family: var(--font-body);
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  min-width: 36px;
  min-height: 32px;
  box-sizing: border-box;
  line-height: 1;
  text-decoration: none;
}

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

.hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--color-text);
}

.hamburger svg { width: 24px; height: 24px; }

.mobile-menu {
  display: none;
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--color-bg);
  z-index: 999;
  padding: 24px;
  flex-direction: column;
  gap: 4px;
  overflow-y: auto;
}

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

.mobile-menu a:not(.nav-btn) {
  display: block;
  padding: 14px 16px;
  border-radius: var(--radius-md);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text-muted);
}

.mobile-menu a:not(.nav-btn):hover,
.mobile-menu a:not(.nav-btn).active {
  background: var(--color-accent-light);
  color: var(--color-accent);
}

.mobile-menu .mobile-actions {
  display: none;
}

.mobile-menu .mobile-theme-toggle {
  display: none;
}

@media (max-width: 768px) {
  .mobile-menu .mobile-theme-toggle {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    margin-top: 16px;
    padding: 14px 16px;
    border: none;
    border-top: 1px solid var(--color-border);
    background: none;
    color: var(--color-text-muted);
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    border-radius: 0;
    transition: color var(--transition);
  }

  .mobile-menu .mobile-theme-toggle:hover {
    color: var(--color-accent);
  }
}

/* 5. Hero Section */
.hero {
  position: relative;
  overflow: hidden;
  padding: 0;
}

.hero-banner {
  position: relative;
  width: 100%;
  min-height: 420px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--nav-height) + 48px) 24px 48px;
  background: url('../images/background.webp') center center / cover no-repeat;
}

.hero-banner::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(0,0,0,0.45) 0%, rgba(0,0,0,0.55) 100%);
}

[data-theme="dark"] .hero-banner::after {
  background: linear-gradient(180deg, rgba(0,0,0,0.6) 0%, rgba(0,0,0,0.7) 100%);
}

.hero-banner-content {
  position: relative;
  z-index: 1;
}

.hero-banner-content h1 {
  font-size: clamp(2.5rem, 6vw, 4rem);
  color: #ffffff;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.hero-banner-content h1 .accent {
  color: #93c5fd;
}

.hero-banner-content .hero-tagline {
  font-size: clamp(1rem, 2.5vw, 1.35rem);
  color: rgba(255,255,255,0.85);
  font-weight: 500;
  margin-bottom: 8px;
}

.mobile-br { display: none; }

@media (max-width: 768px) {
  .mobile-br { display: block; }
}

.hero-banner-content .hero-institution {
  font-size: 0.95rem;
  color: rgba(255,255,255,0.65);
  font-weight: 400;
}

/* Content sections */
.content-section {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: clamp(48px, 6vw, 72px) 0;
}

.content-section .section-title {
  margin-bottom: 24px;
}

.content-section .section-subtitle {
  color: var(--color-text-subtle);
  font-size: 0.9rem;
  margin-bottom: 24px;
  padding-left: 20px;
}

.content-section-body {
  padding-left: 20px;
}

.content-section-body p {
  font-size: 1rem;
  color: var(--color-text-muted);
  line-height: 1.85;
}

.content-section-body .mission {
  font-size: 0.95rem;
  color: var(--color-accent);
  font-weight: 500;
  font-style: italic;
  margin-bottom: 0;
  padding: 14px 18px;
  background: var(--color-accent-light);
  border-radius: var(--radius-md);
  border-left: 3px solid var(--color-accent);
}

/* Research Graph */
.research-graph-section {
  padding: clamp(48px, 8vw, 80px) 0;
}

.research-graph-section .section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  margin-top: -24px;
  margin-bottom: 32px;
  font-size: 0.95rem;
}

#researchGraph {
  width: 100%;
  max-width: 900px;
  margin: 0 auto;
  display: block;
  cursor: grab;
}

#researchGraph:active {
  cursor: grabbing;
}

#researchGraph text {
  font-family: var(--font-body);
  pointer-events: none;
  user-select: none;
}

#researchGraph .graph-edge {
  stroke: var(--color-border);
  stroke-width: 2;
  fill: none;
  transition: stroke var(--transition);
}

#researchGraph .graph-node {
  cursor: pointer;
  transition: filter var(--transition);
}

#researchGraph .graph-node:hover {
  filter: brightness(1.15);
}

.graph-tooltip {
  position: fixed;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 8px 12px;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  box-shadow: var(--shadow-md);
  pointer-events: none;
  z-index: 100;
  max-width: 240px;
  opacity: 0;
  transition: opacity 0.15s ease;
}

/* 6. Cards */
.card-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all var(--transition);
}

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

.card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  font-size: 1.5rem;
}

.card h3 { font-family: var(--font-body); font-weight: 600; }
.card p { color: var(--color-text-muted); font-size: 0.925rem; margin-bottom: 0; }

/* 7. Publication List */
.pub-list { list-style: none; }

.pub-item {
  padding: 20px 0;
  border-bottom: 1px solid var(--color-border-light);
}

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

.pub-year {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-accent);
  background: var(--color-accent-light);
  padding: 2px 10px;
  border-radius: var(--radius-pill);
  margin-bottom: 6px;
}

.pub-title {
  font-weight: 600;
  font-size: 1rem;
  margin-bottom: 4px;
  color: var(--color-text);
}

.pub-authors {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.pub-venue {
  font-size: 0.85rem;
  color: var(--color-text-subtle);
  font-style: italic;
}

.pub-category {
  margin-bottom: 48px;
}

.pub-category-title {
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 1.1rem;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-accent);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.pub-count {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-accent);
  background: var(--color-accent-light);
  padding: 2px 8px;
  border-radius: var(--radius-pill);
}

/* 8. Member Cards */
.professor-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: clamp(28px, 4vw, 40px);
  margin-bottom: 48px;
}

.professor-header {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  margin-bottom: 24px;
}

.professor-photo {
  width: 200px;
  height: 200px;
  border-radius: var(--radius-lg);
  object-fit: cover;
  flex-shrink: 0;
  box-shadow: var(--shadow-md);
}

.professor-info h2 { margin-bottom: 6px; font-size: 1.5rem; }
.professor-info .title-text { color: var(--color-accent); font-weight: 600; font-size: 1rem; margin-bottom: 2px; }
.professor-info .dept-text { color: var(--color-text-subtle); font-size: 0.9rem; margin-bottom: 12px; }

.professor-contact-inline {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--color-text-subtle);
  flex-wrap: wrap;
}

.professor-contact-inline a {
  color: var(--color-accent);
  font-weight: 500;
}

.professor-contact-block {
  margin-top: 12px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.professor-contact-row {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--color-text-subtle);
}

.professor-contact-row svg {
  flex-shrink: 0;
  color: var(--color-text-subtle);
}

.professor-contact-row a {
  color: var(--color-accent);
  font-weight: 500;
}

.professor-social-links {
  display: flex;
  gap: 10px;
  margin-top: 8px;
}

.professor-social-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-muted);
  transition: all var(--transition);
}

.professor-social-btn:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.professor-social-btn svg {
  flex-shrink: 0;
}

.professor-details { margin-top: 24px; }

.detail-section { margin-bottom: 24px; }
.detail-section h4 {
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: 10px;
  padding-bottom: 6px;
  border-bottom: 2px solid var(--color-accent-light);
}

.detail-list {
  list-style: none;
}

.detail-list li {
  padding: 6px 0;
  font-size: 0.925rem;
  color: var(--color-text-muted);
  display: flex;
  gap: 8px;
}

.detail-list li .period {
  font-weight: 600;
  color: var(--color-text);
  white-space: nowrap;
  min-width: 110px;
}


.student-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
}

.student-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  text-align: center;
  transition: all var(--transition);
}

.student-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-sm);
}

.student-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-bg-card);
  color: var(--color-text-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  font-weight: 600;
  margin: 0 auto 12px;
}

.student-card .name { font-weight: 600; font-size: 0.95rem; }
.student-card .role { font-size: 0.8rem; color: var(--color-text-subtle); }

/* Student tabs */
.student-tabs {
  display: flex;
  gap: 6px;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.student-tab {
  padding: 8px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: none;
  color: var(--color-text-muted);
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
}

.student-tab:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.student-tab.active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: white;
}

.student-category {
  margin-bottom: 28px;
}

.student-category-title {
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.student-count {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-accent);
  background: var(--color-accent-light);
  padding: 2px 8px;
  border-radius: var(--radius-pill);
}

.recruiting-banner {
  background: var(--color-accent-light);
  border: 1px solid var(--color-accent);
  border-radius: var(--radius-lg);
  padding: 24px 28px;
  text-align: center;
  margin-top: 32px;
}

.recruiting-banner h3 { color: var(--color-accent); margin-bottom: 8px; }
.recruiting-banner p { color: var(--color-text-muted); margin-bottom: 0; font-size: 0.95rem; }

/* 8b. About Page */
.about-img-wrap {
  margin-top: 24px;
}

.about-content-img {
  width: 100%;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.about-research-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.about-research-item {
  padding: 24px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-bg);
  transition: all var(--transition);
}

.about-research-item:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.about-research-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 14px;
}

.about-research-item h3 {
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.about-research-item p {
  font-size: 0.9rem;
  color: var(--color-text-subtle);
  margin-bottom: 0;
  line-height: 1.6;
}

/* 8c. Album Page */
.album-category {
  margin-bottom: 48px;
}

.album-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.album-item {
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  transition: all var(--transition);
}

.album-item:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
  border-color: var(--color-accent);
}

.album-photo {
  width: 100%;
  height: 220px;
  object-fit: cover;
  display: block;
}

.album-caption {
  padding: 10px 14px 4px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text);
}

.album-date {
  padding: 0 14px 10px;
  font-size: 0.8rem;
  color: var(--color-text-subtle);
}

@media (max-width: 1024px) {
  .album-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .album-grid { grid-template-columns: 1fr; }
}

.album-empty {
  text-align: center;
  padding: clamp(60px, 10vw, 120px) 20px;
  background: var(--color-bg-alt);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-xl);
}

.album-empty-icon {
  color: var(--color-text-subtle);
  margin-bottom: 20px;
  opacity: 0.5;
}

.album-empty h3 {
  font-family: var(--font-body);
  color: var(--color-text-muted);
  margin-bottom: 8px;
}

.album-empty p {
  color: var(--color-text-subtle);
  font-size: 0.95rem;
  margin-bottom: 0;
}

@media (max-width: 1024px) {
  .about-research-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .about-research-grid { grid-template-columns: 1fr; }
  .about-hero-img { max-height: 250px; }
}

/* 9. Teaching */
.semester-block {
  margin-bottom: 48px;
}

.semester-block .section-title {
  margin-bottom: 16px;
}

.teaching-items {
  padding-left: 20px;
}

.teaching-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--color-border-light);
}

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

.teaching-accent {
  width: 4px;
  min-height: 36px;
  background: #94a3b8;
  border-radius: 2px;
  flex-shrink: 0;
  align-self: stretch;
}

.teaching-body {
  flex: 1;
}

.teaching-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 3px;
}

.teaching-grade {
  font-size: 0.85rem;
  color: var(--color-text-subtle);
  font-weight: 500;
}

/* 10. Contact */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.contact-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: all var(--transition);
}

.contact-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-sm);
}

.contact-card .label {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-subtle);
  margin-bottom: 8px;
}

.contact-card .value {
  font-size: 0.95rem;
  color: var(--color-text);
  font-weight: 500;
}

.map-embed {
  margin-top: 32px;
}

/* 11. Footer */
.site-footer {
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  padding: 40px 0;
  margin-top: 48px;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 48px);
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
}

.footer-brand {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  margin-bottom: 8px;
  color: var(--color-text);
}

.footer-info {
  font-size: 0.85rem;
  color: var(--color-text-subtle);
  line-height: 1.8;
}

.footer-copy {
  font-size: 0.8rem;
  color: var(--color-text-subtle);
  text-align: right;
  white-space: nowrap;
}

/* 12. Animations */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* 13. Utility */
.page-header {
  padding: calc(var(--nav-height) + clamp(36px, 6vw, 60px)) 0 clamp(24px, 4vw, 40px);
  text-align: center;
}

.page-header p {
  color: var(--color-text-muted);
  max-width: 560px;
  margin: 0 auto;
  font-size: 1.05rem;
}

.text-center { text-align: center; }
.mt-2 { margin-top: 16px; }
.mt-4 { margin-top: 32px; }
.mb-2 { margin-bottom: 16px; }

/* 13b. Member Toggle */
.member-toggle-wrap {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-bottom: 36px;
}

.member-toggle {
  padding: 10px 28px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: none;
  color: var(--color-text-muted);
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
}

.member-toggle:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.member-toggle.active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: white;
}

/* 14. Responsive */
@media (max-width: 1024px) {
  .card-grid { grid-template-columns: repeat(2, 1fr); }
}

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

  .nav-links { display: none; }
  .nav-actions .theme-toggle { display: none; }
  .nav-right { gap: 8px; }
  .hamburger { display: block; }

  .hero-banner { min-height: 300px; }
  .hero-banner-content h1 { font-size: 2.25rem; }

  .about-research-item { padding: 20px 16px; }
  .teaching-items { padding-left: 0; }

  .content-section-body { padding-left: 0; }

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

  .professor-header { flex-direction: column; align-items: center; text-align: center; }
  .professor-photo { width: 160px; height: 160px; }
  .professor-contact-inline { justify-content: center; }

  .footer-inner { flex-direction: column; text-align: center; align-items: stretch; }
  .footer-copy { text-align: center; }

  .detail-list li { flex-direction: column; gap: 2px; }
  .detail-list li .period { min-width: auto; }
}

@media (max-width: 480px) {
  .student-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .hero-banner { min-height: 240px; padding-top: calc(var(--nav-height) + 32px); padding-bottom: 32px; }
  .hero-banner-content h1 { font-size: 2rem; }
  .section-title { font-size: 1.25rem; }
  .nav-brand .brand-logo { height: 28px; }
  .nav-brand .brand-logo-univ { height: 24px; margin-left: 8px; }
  .professor-card { padding: 20px; }
  .pub-title { font-size: 0.95rem; }
}