:root {
  --cornell-red: #B31B1B;
  --cornell-red-dark: #8C1515;
  --cornell-red-light: #D44D4D;
  --cornell-red-10: #B31B1B18;
  --cornell-red-05: #B31B1B0C;
  --black: #1a1a1a;
  --gray-900: #222222;
  --gray-800: #333333;
  --gray-700: #444444;
  --gray-600: #555555;
  --gray-500: #777777;
  --gray-400: #999999;
  --gray-300: #bbbbbb;
  --gray-200: #dddddd;
  --gray-100: #f0f0f0;
  --gray-50: #f8f7f6;
  --white: #ffffff;
  --mono: 'DM Mono', monospace;
  --serif: 'Instrument Serif', Georgia, serif;
  --sans: 'DM Sans', system-ui, sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  background: var(--white);
  color: var(--black);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

/* ── NAV ── */
nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-bottom: 1px solid var(--gray-200);
  transition: box-shadow 0.3s;
}

nav.scrolled { box-shadow: 0 1px 20px rgba(0,0,0,0.06); }

.nav-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 2.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 110px;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
}

.nav-logo img {
  height: 96px;
  width: auto;
}

.nav-links {
  display: flex;
  gap: 2.5rem;
}

.nav-links a {
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--gray-600);
  text-decoration: none;
  transition: color 0.2s;
  position: relative;
}

.nav-links a:hover { color: var(--cornell-red); }
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1.5px;
  background: var(--cornell-red);
  transition: width 0.3s;
}
.nav-links a:hover::after { width: 100%; }

.hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  width: 26px;
  height: 18px;
  position: relative;
}
.hamburger span {
  display: block;
  width: 100%;
  height: 1.5px;
  background: var(--black);
  position: absolute;
  left: 0;
  transition: 0.3s;
}
.hamburger span:nth-child(1) { top: 0; }
.hamburger span:nth-child(2) { top: 50%; transform: translateY(-50%); }
.hamburger span:nth-child(3) { bottom: 0; }

/* ── CONTAINER ── */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 2.5rem;
}

/* ── HERO ── */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-top: 110px;
  position: relative;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  top: 0;
  right: -10%;
  width: 60%;
  height: 100%;
  background:
    radial-gradient(ellipse at 70% 40%, var(--cornell-red-10) 0%, transparent 60%),
    radial-gradient(ellipse at 30% 80%, var(--cornell-red-05) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
}

.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0,0,0,0.018) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,0,0,0.018) 1px, transparent 1px);
  background-size: 80px 80px;
  pointer-events: none;
  z-index: 0;
  mask-image: radial-gradient(ellipse 70% 60% at 60% 50%, black, transparent);
  -webkit-mask-image: radial-gradient(ellipse 70% 60% at 60% 50%, black, transparent);
}

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

.hero-tag {
  font-family: var(--mono);
  font-size: 0.65rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cornell-red);
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  opacity: 0;
  animation: fadeUp 0.7s 0.1s forwards;
}

.hero-tag::before {
  content: '';
  width: 24px;
  height: 1.5px;
  background: var(--cornell-red);
}

.hero h1 {
  font-family: var(--serif);
  font-size: clamp(3rem, 6.5vw, 5.8rem);
  font-weight: 400;
  line-height: 1.05;
  letter-spacing: -0.025em;
  color: var(--black);
  margin-bottom: 2rem;
  opacity: 0;
  animation: fadeUp 0.7s 0.25s forwards;
}

.hero h1 em {
  color: var(--cornell-red);
  font-style: italic;
}

.hero-desc {
  font-size: 1.1rem;
  line-height: 1.75;
  color: var(--gray-600);
  max-width: 560px;
  opacity: 0;
  animation: fadeUp 0.7s 0.4s forwards;
}

.hero-stats {
  display: flex;
  gap: 4rem;
  margin-top: 3.5rem;
  opacity: 0;
  animation: fadeUp 0.7s 0.55s forwards;
}

.stat {
  position: relative;
  padding-left: 1.25rem;
}

.stat::before {
  content: '';
  position: absolute;
  left: 0;
  top: 2px;
  bottom: 2px;
  width: 2px;
  background: var(--cornell-red);
  border-radius: 1px;
}

.stat-num {
  font-family: var(--mono);
  font-size: 2rem;
  font-weight: 500;
  color: var(--cornell-red);
  line-height: 1;
}

.stat-label {
  font-family: var(--mono);
  font-size: 0.6rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--gray-500);
  margin-top: 0.4rem;
}

/* ── SECTIONS ── */
section { padding: 7rem 0; }

.section-head {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 3.5rem;
}

.section-idx {
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--cornell-red);
  letter-spacing: 0.05em;
  min-width: 28px;
}

.section-title {
  font-family: var(--serif);
  font-size: clamp(2rem, 3.5vw, 2.8rem);
  font-weight: 400;
  letter-spacing: -0.01em;
}

.section-rule {
  flex: 1;
  height: 1px;
  background: var(--gray-200);
}

/* ── RESEARCH ── */
.research-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--gray-200);
  border: 1px solid var(--gray-200);
  border-radius: 8px;
  overflow: hidden;
}

.r-card {
  background: var(--white);
  padding: 2.25rem;
  transition: background 0.3s;
  position: relative;
}

.r-card:hover { background: var(--gray-50); }

.r-card-icon {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: var(--cornell-red-10);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  margin-bottom: 1.1rem;
}

.r-card h3 {
  font-family: var(--sans);
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.65rem;
  color: var(--black);
}

.r-card p {
  font-size: 0.82rem;
  line-height: 1.65;
  color: var(--gray-500);
}

.r-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-top: 1rem;
}

.r-tag {
  font-family: var(--mono);
  font-size: 0.5rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.2rem 0.55rem;
  border: 1px solid var(--gray-200);
  border-radius: 3px;
  color: var(--gray-500);
}

/* ── PEOPLE ── */
.people-label {
  font-family: var(--mono);
  font-size: 0.6rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cornell-red);
  margin-bottom: 1.25rem;
  margin-top: 3rem;
}

.people-label:first-of-type { margin-top: 0; }

/* PI */
.pi-card {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 2.5rem;
  padding: 2.5rem;
  background: var(--gray-50);
  border: 1px solid var(--gray-200);
  border-radius: 8px;
  margin-bottom: 2.5rem;
}

.pi-photo {
  width: 220px;
  height: 260px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--gray-100), var(--gray-200));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  border: 1px solid var(--gray-200);
  overflow: hidden;
}

.pi-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.pi-info h3 {
  font-family: var(--serif);
  font-size: 1.8rem;
  font-weight: 400;
  margin-bottom: 0.35rem;
}

.pi-role {
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--cornell-red);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 1.15rem;
}

.pi-bio {
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--gray-600);
  max-width: 600px;
  margin-bottom: 1.25rem;
}

.pi-links { display: flex; gap: 0.75rem; flex-wrap: wrap; }

.pi-link {
  font-family: var(--mono);
  font-size: 0.6rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--gray-600);
  text-decoration: none;
  padding: 0.4rem 0.9rem;
  border: 1px solid var(--gray-200);
  border-radius: 4px;
  transition: all 0.2s;
}

.pi-link:hover {
  border-color: var(--cornell-red);
  color: var(--cornell-red);
}

/* Member Grid */
.members-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1px;
  background: var(--gray-200);
  border: 1px solid var(--gray-200);
  border-radius: 8px;
  overflow: hidden;
  margin-bottom: 2rem;
}

.member {
  background: var(--white);
  padding: 1.5rem;
  transition: background 0.3s;
}

.member:hover { background: var(--gray-50); }

.member-avatar {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: var(--cornell-red-10);
  border: 2px solid var(--gray-200);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  margin-bottom: 1rem;
  color: var(--cornell-red);
  font-family: var(--mono);
  font-weight: 500;
  overflow: hidden;
}

.member-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.member h4 {
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.15rem;
}

.member .m-role {
  font-family: var(--mono);
  font-size: 0.55rem;
  color: var(--gray-400);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.member .m-focus {
  font-size: 0.78rem;
  color: var(--gray-500);
  line-height: 1.55;
}

.member a {
  font-family: var(--mono);
  font-size: 0.55rem;
  color: var(--cornell-red);
  text-decoration: none;
  letter-spacing: 0.05em;
  margin-top: 0.5rem;
  display: inline-block;
}

/* Alumni */
.alumni-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 0;
}

.alumni-item {
  font-size: 0.82rem;
  color: var(--gray-600);
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--gray-100);
}

.alumni-item span {
  font-family: var(--mono);
  font-size: 0.6rem;
  color: var(--gray-400);
}

.alumni-cat {
  font-family: var(--mono) !important;
  font-size: 0.5rem !important;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  margin-right: 0.25rem;
  vertical-align: middle;
}

.alumni-cat.faculty {
  border: 1px solid #2a7d4f;
  color: #2a7d4f !important;
}

.alumni-cat.founder {
  border: 1px solid #b57a14;
  color: #b57a14 !important;
}

.alumni-cat.industry {
  border: 1px solid #4a6fa5;
  color: #4a6fa5 !important;
}

/* ── PUBLICATIONS ── */
.pub-list { list-style: none; }

.pub {
  display: grid;
  grid-template-columns: 55px 1fr auto;
  gap: 1.25rem;
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--gray-100);
  align-items: start;
  transition: background 0.2s;
}

.pub:hover {
  background: var(--gray-50);
  margin: 0 -1rem;
  padding: 1.25rem 1rem;
  border-radius: 4px;
}

.pub-year {
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--cornell-red);
  font-weight: 500;
  padding-top: 0.2rem;
}

.pub-title {
  font-family: var(--serif);
  font-size: 1rem;
  font-weight: 400;
  margin-bottom: 0.25rem;
  line-height: 1.4;
  color: var(--black);
}

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

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

.pub-authors {
  font-size: 0.72rem;
  color: var(--gray-400);
  margin-bottom: 0.2rem;
}

.pub-venue {
  font-family: var(--serif);
  font-size: 0.7rem;
  font-style: italic;
  color: var(--gray-400);
}

.pub-badge {
  font-family: var(--mono);
  font-size: 0.5rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.2rem 0.5rem;
  border-radius: 3px;
  white-space: nowrap;
  align-self: center;
}

.pub-badge.c { border: 1px solid var(--cornell-red); color: var(--cornell-red); }
.pub-badge.j { border: 1px solid var(--gray-400); color: var(--gray-400); }
.pub-badge.a { border: 1px solid #c59a1a; color: #c59a1a; background: #c59a1a0a; }

.pub-more {
  text-align: center;
  margin-top: 2.5rem;
}

.pub-more a {
  font-family: var(--mono);
  font-size: 0.65rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--cornell-red);
  text-decoration: none;
  padding: 0.7rem 2rem;
  border: 1px solid var(--cornell-red);
  border-radius: 4px;
  transition: all 0.2s;
  display: inline-block;
}

.pub-more a:hover {
  background: var(--cornell-red);
  color: var(--white);
}

/* ── NEWS ── */
.news-grid {
  display: grid;
  gap: 0;
}

.news-item {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 1.5rem;
  padding: 1rem 0;
  border-bottom: 1px solid var(--gray-100);
}

.news-date {
  font-family: var(--mono);
  font-size: 0.6rem;
  color: var(--gray-400);
  padding-top: 0.15rem;
}

.news-text {
  font-size: 0.85rem;
  color: var(--gray-600);
  line-height: 1.6;
}

.news-text strong { color: var(--black); font-weight: 600; }
.news-text a { color: var(--cornell-red); text-decoration: none; }

/* ── CONTACT ── */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--gray-200);
  border: 1px solid var(--gray-200);
  border-radius: 8px;
  overflow: hidden;
}

.contact-block {
  background: var(--white);
  padding: 2.5rem;
}

.contact-block h3 {
  font-family: var(--mono);
  font-size: 0.6rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--gray-400);
  margin-bottom: 1rem;
}

.contact-block p {
  font-size: 0.9rem;
  color: var(--gray-600);
  line-height: 1.85;
}

.contact-block a {
  color: var(--cornell-red);
  text-decoration: none;
}

.contact-block a:hover { text-decoration: underline; }

/* ── FOOTER ── */
footer {
  padding: 3rem 0;
  border-top: 1px solid var(--gray-200);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

footer p {
  font-family: var(--mono);
  font-size: 0.55rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--gray-400);
}

.footer-logo img { height: 72px; opacity: 0.5; }

/* ── ANIMATIONS ── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

.fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

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

/* ── RESPONSIVE ── */
@media (max-width: 900px) {
  .research-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 110px;
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    padding: 1.5rem 2.5rem;
    border-bottom: 1px solid var(--gray-200);
    gap: 1rem;
  }
  .nav-links.open { display: flex; }
  .hamburger { display: block; }
  .research-grid { grid-template-columns: 1fr; }
  .pi-card { grid-template-columns: 1fr; }
  .pi-photo { width: 100%; height: 200px; }
  .hero-stats { gap: 2rem; flex-wrap: wrap; }
  .contact-grid { grid-template-columns: 1fr; }
  .pub { grid-template-columns: 1fr; gap: 0.4rem; }
  .pub-year { font-size: 0.6rem; }
  .pub-badge { justify-self: start; }
  .news-item { grid-template-columns: 80px 1fr; gap: 0.75rem; }
  .footer-inner { flex-direction: column; gap: 0.75rem; }
  section { padding: 4.5rem 0; }
  .container { padding: 0 1.5rem; }
  .nav-inner { padding: 0 1.5rem; }
}

/* ── SCROLLBAR ── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--white); }
::-webkit-scrollbar-thumb { background: var(--gray-300); border-radius: 3px; }

section.section-muted { background: var(--gray-50); }