/* =====================================================
   FlexML Research Group - Main Stylesheet
   Inspired by Yale FDS design aesthetic
   ===================================================== */

/* --- Google Fonts --- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=Playfair+Display:wght@700;800&display=swap');

/* --- CSS Variables --- */
:root {
  --primary: #1a1a2e;
  --primary-dark: #0d0d1a;
  /* --accent: #4361ee; */
  --accent: rgb(20,135,200); 
  --accent-light: #7289ff;
  --accent-btn: #4361ee;
  --accent-hover: #3451d1;
  --accent-kaist: rgb(20,135,200);
  /* --accent-light-kaist: rgb(95,190,235); */
  --accent-light-kaist: rgb(18, 115, 234);
  --accent-dark-kaist: rgb(0,65,145);
  --accent-medium-kaist: rgb(0,65,135);
  --secondary: #e63946;
  --light-bg: #f8f9fc;
  --border: #e2e8f0;
  --text-primary: #1a1a2e;
  --text-secondary: #4a5568;
  --text-muted: #718096;
  --white: #ffffff;
  --card-shadow: 0 4px 24px rgba(26, 26, 46, 0.08);
  --card-shadow-hover: 0 12px 40px rgba(67, 97, 238, 0.18);
  --nav-height: 72px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  scrollbar-gutter: stable; 
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--text-primary);
  background-color: var(--white);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  /* color: var(--accent); */
  color: var(--accent-medium-kaist);
  text-decoration: none;
  transition: var(--transition);
}

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

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

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

h1 { font-size: clamp(2.2rem, 5vw, 3.8rem); }
h2 { font-size: clamp(1.8rem, 3.5vw, 2.6rem); }
h3 { font-size: clamp(1.3rem, 2.5vw, 1.7rem); }
h4 { font-size: 1.2rem; }

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

/* --- Layout Utilities --- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.container--wide {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 2rem;
}

.section {
  padding: 80px 0;
}

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

/* =====================================================
   NAVIGATION
   ===================================================== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  /* background: transparent; */
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
  border-bottom: 1px solid transparent;
  transition: var(--transition);
}

.nav.scrolled {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 2px 20px rgba(26, 26, 46, 0.1);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.nav__logo-mark {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  background: var(--primary);
  border-radius: 10px;
  position: relative;
  overflow: hidden;
}

.nav__logo-mark::before {
  content: '';
  position: absolute;
  width: 28px;
  height: 28px;
  background: var(--accent);
  border-radius: 50%;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.nav__logo-mark::after {
  content: 'F';
  position: absolute;
  color: white;
  font-weight: 900;
  font-size: 1.1rem;
  z-index: 1;
}

.nav__logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.nav__logo-name {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.02em;
}

.nav__logo-name span {
  /* color: var(--accent); */
  /* color: var(--accent-medium-kaist); */
  color: var(--accent-light-kaist);
}

.nav__logo-sub {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

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

.nav__item a {
  display: block;
  padding: 8px 14px;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-secondary);
  /* color: var(--accent-kaist); */
  border-radius: 8px;
  letter-spacing: 0.01em;
  /* transition: var(--transition); */
  text-decoration: none;
}

.nav__item a:hover,
.nav__item a.active {
  /* color: var(--accent); */
  color: var(--accent-light-kaist);
  background: rgba(67, 97, 238, 0.08);
    /* background:rgba(95,190,235,0.2); */
}

.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 6px;
  border: none;
  background: none;
}

.nav__toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--primary);
  border-radius: 2px;
  transition: var(--transition);
}

/* =====================================================
   HERO SECTION
   ===================================================== */
.hero {
  min-height: 50vh;
  display: flex;
  align-items: center;
  background: var(--primary);
  position: relative;
  overflow: hidden;
  padding-top: var(--nav-height);
}

.hero__bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 70% 50%, rgba(67, 97, 238, 0.3) 0%, transparent 60%),
    radial-gradient(ellipse 50% 50% at 20% 80%, rgba(114, 137, 255, 0.15) 0%, transparent 50%),
    linear-gradient(135deg, #1a1a2e 0%, #0d1b4b 100%);
}

.hero__grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(67, 97, 238, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(67, 97, 238, 0.06) 1px, transparent 1px);
  background-size: 60px 60px;
}

.hero__content {
  position: relative;
  z-index: 2;
  max-width: 1200px;
  margin: 0 auto;
  padding: 80px 2rem;
  display: grid;
  grid-template-columns: 10fr 1fr;
  gap: 60px;
  align-items: center;
  width: 100%;
}

.hero__text {}

.hero__label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(67, 97, 238, 0.2);
  border: 1px solid rgba(67, 97, 238, 0.4);
  /* color: var(--accent-light); */
  color: #e3f2fd;
  padding: 6px 14px;
  border-radius: 50px;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 24px;
}

.hero__label::before {
  content: '';
  width: 16px;
  height: 16px;
  background: var(--accent-light);
  border-radius: 140%;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

.hero__title {
  font-size: clamp(2.8rem, 6vw, 3.5rem);
  font-weight: 900;
  color: var(--white);
  line-height: 1.05;
  letter-spacing: -0.03em;
  margin-bottom: 12px;
}

.hero__title span {
  color: var(--accent-light-kaist);
  font-size: 3rem;
  /* color: rgb(51, 217, 32); */
  /* display: block; */
}

.hero__subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: rgba(255, 255, 255, 0.7);
  margin-bottom: 32px;
  font-weight: 300;
  line-height: 1.6;
}

.hero__dept {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 40px;
}

.hero__dept-badge {
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: rgba(255, 255, 255, 0.85);
  padding: 5px 12px;
  border-radius: 6px;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}

.hero__actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}

.hero__visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero__diagram {
  width: 100%;
  max-width: 460px;
  position: relative;
}

.hero__diagram svg {
  width: 100%;
  height: auto;
  filter: drop-shadow(0 20px 60px rgba(67, 97, 238, 0.4));
}

/* =====================================================
   BUTTONS
   ===================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  cursor: pointer;
  border: 2px solid transparent;
  transition: var(--transition);
  text-decoration: none;
}

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

.btn--primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: white;
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(67, 97, 238, 0.4);
}

.btn--outline {
  background: transparent;
  color: rgba(255, 255, 255, 0.85);
  border-color: rgba(255, 255, 255, 0.3);
}

.btn--outline:hover {
  background: rgba(255, 255, 255, 0.1);
  color: white;
  border-color: rgba(255, 255, 255, 0.6);
  transform: translateY(-2px);
}

.btn--outline-dark {
  background: transparent;
  color: var(--accent-light-kaist);
  border-color: var(--accent-light-kaist);
}

.btn--outline-dark:hover {
  background: var(--accent-light-kaist);
  color: white;
  transform: translateY(-2px);
}

.btn--sm {
  padding: 8px 18px;
  font-size: 0.8rem;
}

/* =====================================================
   SECTION HEADERS
   ===================================================== */
.section-header {
  margin-bottom: 56px;
}

.section-header--center {
  text-align: center;
}

.section-tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  background: rgba(67, 97, 238, 0.08);
  padding: 4px 12px;
  border-radius: 4px;
  margin-bottom: 14px;
}

.section-title {
  font-size: clamp(1.8rem, 3.5vw, 2.6rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--primary);
  margin-bottom: 16px;
}

.section-desc {
  font-size: 1.25rem;
  /* color: var(--text-muted); */
  font-family:'Times New Roman', Times, serif
  color: black;
  max-width: 1600px;
  line-height: 1.6;
}

.section-header--center .section-desc {
  margin: 0 auto;
}

/* =====================================================
   STATS BAR
   ===================================================== */
.stats-bar {
  background: var(--accent);
  padding: 40px 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: rgba(255, 255, 255, 0.2);
}

.stat-item {
  background: var(--accent);
  text-align: center;
  padding: 28px 20px;
}

.stat-number {
  font-size: 2.8rem;
  font-weight: 900;
  color: white;
  line-height: 1;
  letter-spacing: -0.03em;
  margin-bottom: 6px;
}

.stat-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.75);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* =====================================================
   RESEARCH CARDS
   ===================================================== */
.research-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.research-card {
  background: white;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 36px 32px;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.research-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--accent);
  transform: scaleX(0);
  transition: var(--transition);
  transform-origin: left;
}

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

.research-card:hover::before {
  transform: scaleX(1);
}

.research-card__icon {
  width: 56px;
  height: 56px;
  background: rgba(67, 97, 238, 0.08);
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
  font-size: 1.6rem;
  transition: var(--transition);
}

.research-card:hover .research-card__icon {
  background: #d8e4f9;
}

.research-card:hover .research-card__icon svg,
.research-card:hover .research-card__icon .icon {
  filter: brightness(10);
}

.research-card__title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 12px;
  line-height: 1.3;
}

.research-card__desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 20px;
}

.research-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--accent);
  background: rgba(67, 97, 238, 0.08);
  padding: 3px 10px;
  border-radius: 4px;
  letter-spacing: 0.02em;
}

/* =====================================================
   NEWS / UPDATES
   ===================================================== */
.news-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  /* font-size: 1.2rem; */
}

.news-item {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 32px;
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
}

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

.news-item:hover {
  background: rgba(67, 97, 238, 0.02);
  margin: 0 -20px;
  padding: 14px 20px;
  border-radius: 8px;
  border-color: transparent;
}

.news-date {
  font-size: 0.8rem;
  font-weight: 700;
  /* color: var(--accent); */
  color: var(--accent-btn);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding-top: 4px;
}

.news-content {
  /* display: flex; */
  align-items: baseline;
  gap: 8px;
  flex-wrap: wrap;
}

.news-badge {
  display: inline-block;
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 4px;
  margin-bottom: 8px;
}

.news-badge--paper { background: #e8f5e9; color: #2e7d32; }
.news-badge--award { background: #fff3e0; color: #e65100; }
.news-badge--talk { background: #e3f2fd; color: #1565c0; }
.news-badge--join { background: #f3e5f5; color: #6a1b9a; }
.news-badge--misc { background: #f5f5f5; color: #424242; }

.news-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--primary);
  line-height: 1.5;
  margin-bottom: 6px;
}

.news-title a {
  color: var(--primary);
}

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

.news-meta {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* =====================================================
   PUBLICATIONS
   ===================================================== */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.pub-item {
  background: white;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 28px 32px;
  transition: var(--transition);
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 24px;
  align-items: start;
}

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

.pub-year {
  font-size: 0.75rem;
  font-weight: 800;
  color: var(--accent);
  background: rgba(67, 97, 238, 0.08);
  padding: 4px 10px;
  border-radius: 6px;
  white-space: nowrap;
  margin-top: 4px;
}

.pub-content {}

.pub-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 8px;
  line-height: 1.5;
}

.pub-title a {
  color: var(--primary);
}

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

.pub-authors {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 6px;
  line-height: 1.5;
}

.pub-authors strong {
  color: var(--primary);
  font-weight: 700;
}

.pub-venue {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: 12px;
}

.pub-venue strong {
  font-style: normal;
  font-weight: 700;
  color: var(--accent-light-kaist);
}

.pub-links {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.pub-link {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 4px 12px;
  border-radius: 6px;
  border: 1.5px solid;
  transition: var(--transition);
}

.pub-link--arxiv { color: #b5451b; border-color: #b5451b; }
.pub-link--arxiv:hover { background: #b5451b; color: white; }
.pub-link--code { color: #155724; border-color: #155724; }
.pub-link--code:hover { background: #155724; color: white; }
.pub-link--pdf { color: var(--accent); border-color: var(--accent); }
.pub-link--pdf:hover { background: var(--accent); color: white; }
.pub-link--website { color: #6f42c1; border-color: #6f42c1; }
.pub-link--website:hover { background: #6f42c1; color: white; }

.pub-year-group + .pub-year-group {
  margin-top: 48px;
}

/* =====================================================
   PEOPLE
   ===================================================== */
.people-section-title {
  font-size: 1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 28px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--border);
}

.people-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-bottom: 56px;
}

.people-grid--lg {
  grid-template-columns: repeat(2, 1fr);
}

.person-card {
  background: white;
  border: 1px solid var(--border);
  border-radius: 16px;
  overflow: hidden;
  transition: var(--transition);
  text-align: center;
}

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

.person-card__photo {
  width: 100%;
  aspect-ratio: 1;
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  font-weight: 800;
  color: white;
  letter-spacing: -0.02em;
  overflow: hidden;
}

.person-card__photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.person-card__info {
  padding: 20px 16px;
}

.person-card__name {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
}

.person-card__role {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent);
  /* color: var(--accent-medium-kaist); */
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 8px;
}

.person-card__research {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin-bottom: 14px;
}

.person-card__links {
  display: flex;
  justify-content: center;
  gap: 8px;
}

.person-link {
  width: 30px;
  height: 30px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  border: 1.5px solid var(--border);
  color: var(--text-muted);
  font-size: 0.75rem;
  transition: var(--transition);
}

.person-link:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(67, 97, 238, 0.06);
}

/* PI Card */
.pi-card {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 40px;
  background: white;
  border: 1px solid var(--border);
  border-radius: 20px;
  overflow: hidden;
  padding: 40px;
  margin-bottom: 56px;
  align-items: center;
  transition: var(--transition);
}

.pi-card:hover {
  box-shadow: var(--card-shadow-hover);
}

.pi-card__photo {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
  font-weight: 800;
  color: white;
  overflow: hidden;
  flex-shrink: 0;
  border: 1px solid lightgrey;
}

.pi-card__photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.pi-card__name {
  font-size: 1.8rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 4px;
}

.pi-card__title {
  font-size: 0.9rem;
  font-weight: 600;
  /* color: var(--accent); */
  /* color: #0991e6; */
  color: var(--accent-light-kaist);
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.pi-card__bio {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
}

.pi-card__links {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

/* =====================================================
   CONTACT
   ===================================================== */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: start;
}

.contact-info-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
  margin-top: 32px;
}

.contact-info-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.contact-info-icon {
  width: 44px;
  height: 44px;
  background: rgba(67, 97, 238, 0.08);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 1.1rem;
}

.contact-info-text strong {
  display: block;
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.contact-info-text span,
.contact-info-text a {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

.contact-map {
  background: var(--light-bg);
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  min-height: 360px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.contact-map iframe {
  width: 100%;
  height: 360px;
  border: none;
}

/* =====================================================
   FOOTER
   ===================================================== */
.footer {
  background: var(--primary-dark);
  color: rgba(255, 255, 255, 0.6);
  padding: 25px 0 30px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.footer__inner {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 48px;
  margin-bottom: 48px;
}

.footer__brand {}

.footer__logo {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
  text-decoration: none;
}

.footer__logo-text {
  font-size: 1.3rem;
  font-weight: 800;
  color: white;
}

.footer__logo-text span {
  color: var(--accent-light);
}

.footer__desc {
  font-size: 0.85rem;
  line-height: 1.7;
  margin-bottom: 24px;
  color: rgba(255, 255, 255, 0.5);
}

.footer__social {
  display: flex;
  gap: 10px;
}

.footer__social a {
  width: 36px;
  height: 36px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.85rem;
  transition: var(--transition);
}

.footer__social a:hover {
  background: var(--accent);
  color: white;
}

.footer__col-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: rgba(255, 255, 255, 0.4);
  margin-bottom: 18px;
}

.footer__links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer__links a {
  font-size: 0.875rem;
  color: rgba(255, 255, 255, 0.55);
  text-decoration: none;
  transition: var(--transition);
}

.footer__links a:hover {
  color: white;
}

.footer__bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.footer__copy {
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.35);
}

.footer__kaist {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.35);
}

/* =====================================================
   PAGE HEADER (Inner pages)
   ===================================================== */
.page-header {
  background: var(--primary);
  padding: calc(var(--nav-height) + 60px) 0 60px;
  position: relative;
  overflow: hidden;
}

.page-header__bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 60% 80% at 80% 50%, rgba(67, 97, 238, 0.25) 0%, transparent 60%),
    linear-gradient(135deg, #1a1a2e 0%, #0d1b4b 100%);
}

.page-header__grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(67, 97, 238, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(67, 97, 238, 0.05) 1px, transparent 1px);
  background-size: 60px 60px;
}

.page-header__content {
  position: relative;
  z-index: 2;
}

.page-header__tag {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-light);
  margin-bottom: 12px;
}

.page-header__title {
  font-size: clamp(2rem, 4vw, 3.2rem);
  font-weight: 900;
  color: white;
  letter-spacing: -0.03em;
  margin-bottom: 14px;
}

.page-header__desc {
  font-size: 1.1rem;
  color: rgba(255, 255, 255, 0.65);
  max-width: 560px;
}

/* =====================================================
   FILTER TABS
   ===================================================== */
.filter-tabs {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 40px;
}

.filter-tab {
  padding: 8px 18px;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  border: 1.5px solid var(--border);
  background: white;
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
}

.filter-tab:hover,
.filter-tab.active {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(67, 97, 238, 0.06);
}

/* =====================================================
   FEATURED PAPER
   ===================================================== */
.featured-paper {
  background: linear-gradient(135deg, var(--primary) 0%, #0d1b4b 100%);
  border-radius: 20px;
  padding: 48px;
  margin-bottom: 40px;
  color: white;
  position: relative;
  overflow: hidden;
}

.featured-paper::before {
  content: '';
  position: absolute;
  right: -40px;
  top: -40px;
  width: 240px;
  height: 240px;
  background: rgba(67, 97, 238, 0.2);
  border-radius: 50%;
}

.featured-paper__label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-light);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.featured-paper__title {
  font-size: 1.5rem;
  font-weight: 800;
  color: white;
  margin-bottom: 12px;
  line-height: 1.3;
  letter-spacing: -0.02em;
}

.featured-paper__authors {
  font-size: 0.9rem;
  color: rgba(255, 255, 255, 0.7);
  margin-bottom: 6px;
}

.featured-paper__venue {
  font-size: 0.88rem;
  color: rgba(255, 255, 255, 0.5);
  font-style: italic;
  margin-bottom: 24px;
}

/* =====================================================
   RESEARCH PAGE DEEP DIVE
   ===================================================== */
.research-area {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: center;
  padding: 60px 0;
  border-bottom: 1px solid var(--border);
}

.research-area:last-child {
  border-bottom: none;
}

.research-area--reverse {
  direction: rtl;
}

.research-area--reverse > * {
  direction: ltr;
}

.research-area__visual {
  background: var(--light-bg);
  border-radius: 20px;
  padding: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 280px;
}

.research-area__num {
  font-size: 5rem;
  font-weight: 900;
  color: rgba(67, 97, 238, 0.08);
  line-height: 1;
  margin-bottom: 8px;
  letter-spacing: -0.04em;
}

.research-area__title {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.research-area__desc {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.8;
  margin-bottom: 24px;
}

.research-area__topics {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

/* =====================================================
   UTILITIES
   ===================================================== */
.divider {
  height: 1px;
  background: var(--border);
  margin: 0;
}

.text-center { text-align: center; }
.text-accent { color: var(--accent); }
.font-bold { font-weight: 700; }

.view-all {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  text-decoration: none;
  transition: var(--transition);
}

.view-all:hover {
  gap: 10px;
  /* color: var(--accent-hover); */
  color: violet
}

.view-all::after {
  content: '→';
}

/* =====================================================
   ANIMATIONS
   ===================================================== */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

.animate-in {
  animation: fadeInUp 0.6s ease forwards;
}

/* =====================================================
   RESPONSIVE
   ===================================================== */
@media (max-width: 1024px) {
  .footer__inner {
    grid-template-columns: 1fr 1fr;
    gap: 36px;
  }

  .research-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .people-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 768px) {
  :root { --nav-height: 64px; }

  .nav__menu {
    display: none;
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: white;
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 16px;
    gap: 4px;
    box-shadow: 0 12px 40px rgba(0,0,0,0.1);
  }

  .nav__menu.open { display: flex; }
  .nav__toggle { display: flex; }

  .hero__content {
    grid-template-columns: 1fr;
    padding: 60px 1.5rem;
  }

  .hero__visual { display: none; }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

  .research-area {
    grid-template-columns: 1fr;
  }

  .research-area--reverse { direction: ltr; }

  .people-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .people-grid--lg {
    grid-template-columns: 1fr;
  }

  .pi-card {
    grid-template-columns: 1fr;
    text-align: center;
  }

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

  .news-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .pub-item {
    grid-template-columns: 1fr;
  }

  .footer__inner {
    grid-template-columns: 1fr;
    gap: 32px;
  }

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

  .section { padding: 60px 0; }
}

@media (max-width: 480px) {
  .container { padding: 0 1.25rem; }

  .people-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}