/* =========================================================
   SETTLOR Lab – Modern Stylesheet
   ========================================================= */

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

:root {
  --bg:           #ffffff;
  --bg2:          #ffffff;
  --bg3:          #ffffff;
  --surface:      rgba(99,102,241,0.06);
  --surface-hover:rgba(99,102,241,0.11);
  --border:       rgba(99,102,241,0.15);
  --border-hover: rgba(99,102,241,0.35);
  --accent:       #6366f1;
  --accent-light: #4f46e5;
  --accent-2:     #0284c7;
  --accent-3:     #9333ea;
  --success:      #16a34a;
  --text:         #0f172a;
  --text-muted:   #475569;
  --text-faint:   #94a3b8;
  --radius:       12px;
  --radius-lg:    20px;
  --shadow:       0 4px 32px rgba(99,102,241,0.12);
  --transition:   0.25s cubic-bezier(.4,0,.2,1);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}

/* ─── SCROLLBAR ─────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg2); }
::-webkit-scrollbar-thumb { background: var(--accent); border-radius: 3px; }

/* ─── UTILITY ───────────────────────────────────────────── */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}
.glass {
  background: #ffffff;
  border: 1px solid var(--border);
  box-shadow: 0 2px 16px rgba(99,102,241,0.08);
}
.gradient-text {
  background: linear-gradient(135deg, var(--accent-light), var(--accent-2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ─── BUTTONS ───────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .75rem 1.75rem;
  border-radius: 999px;
  font-size: .95rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
}
.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  box-shadow: 0 0 24px rgba(99,102,241,.4);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 40px rgba(99,102,241,.6);
}
.btn-outline {
  background: #fff;
  color: var(--accent-light);
  border: 1.5px solid var(--border-hover);
}
.btn-outline:hover {
  background: var(--surface-hover);
  border-color: var(--accent);
  color: var(--accent);
}

/* ─── NAVBAR ────────────────────────────────────────────── */
#navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  padding: 1rem 0;
  transition: all var(--transition);
}
#navbar.scrolled {
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: .65rem 0;
}
.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}
.nav-brand {
  display: flex;
  align-items: center;
  gap: .75rem;
  text-decoration: none;
  color: var(--text);
}
.brand-icon {
  width: 38px; height: 38px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border-radius: 10px;
  display: grid;
  place-items: center;
  font-weight: 800;
  font-size: 1.1rem;
  color: #fff;
  flex-shrink: 0;
}
.brand-title { font-weight: 700; font-size: 1rem; line-height: 1.2; }
.brand-sub { font-size: .72rem; color: var(--text-muted); }
.nav-links {
  list-style: none;
  display: flex;
  gap: 2rem;
}
.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: .9rem;
  font-weight: 500;
  transition: color var(--transition);
}
.nav-links a:hover { color: var(--text); }
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 22px; height: 2px;
  background: var(--accent);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ─── HERO ──────────────────────────────────────────────── */
#hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 7rem 2rem 4rem;
  position: relative;
  overflow: hidden;
  background: #ffffff;
}
.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(99,102,241,.1) 1px, transparent 1px),
    linear-gradient(90deg, rgba(99,102,241,.1) 1px, transparent 1px);
  background-size: 60px 60px;
}
.hero-glow {
  position: absolute;
  border-radius: 50%;
  filter: blur(100px);
  opacity: .22;
}
.glow-1 {
  width: 600px; height: 600px;
  background: var(--accent);
  top: -100px; left: -100px;
}
.glow-2 {
  width: 500px; height: 500px;
  background: var(--accent-2);
  bottom: -80px; right: -80px;
}
.hero-content { position: relative; z-index: 1; max-width: 860px; }
.hero-badge {
  display: inline-block;
  padding: .35rem 1.1rem;
  border-radius: 999px;
  border: 1px solid rgba(99,102,241,.4);
  background: rgba(99,102,241,.1);
  color: var(--accent-light);
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  margin-bottom: 1.5rem;
}
.hero-title {
  font-size: clamp(3rem, 8vw, 5.5rem);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: -.03em;
  margin-bottom: 1.5rem;
}
.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 640px;
  margin: 0 auto 2.5rem;
}
.hero-cta { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; margin-bottom: 4rem; }
.hero-stats {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 3rem;
  flex-wrap: wrap;
}
.stat { text-align: center; }
.stat-num {
  display: block;
  font-size: 2.4rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent-light), var(--accent-2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
}
.stat-label { font-size: .78rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: .08em; margin-top: .3rem; }
.stat-divider {
  width: 1px; height: 48px;
  background: var(--border);
}
.hero-scroll {
  position: absolute;
  bottom: 2rem; left: 50%;
  transform: translateX(-50%);
  z-index: 1;
}
.scroll-indicator {
  width: 24px; height: 38px;
  border: 2px solid var(--border-hover);
  border-radius: 12px;
  position: relative;
}
.scroll-indicator::after {
  content: '';
  position: absolute;
  top: 6px; left: 50%;
  transform: translateX(-50%);
  width: 4px; height: 8px;
  background: var(--accent-light);
  border-radius: 2px;
  animation: scrollDot 1.8s infinite;
}
@keyframes scrollDot {
  0%   { opacity: 1; transform: translateX(-50%) translateY(0); }
  100% { opacity: 0; transform: translateX(-50%) translateY(12px); }
}

/* ─── SECTIONS ──────────────────────────────────────────── */
.section { padding: 6rem 0; }
.section-dark { background: #ffffff; }
.section-header { text-align: center; margin-bottom: 3.5rem; }
.section-tag {
  display: inline-block;
  color: var(--accent-light);
  font-size: .78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: .75rem;
}
.section-header h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  letter-spacing: -.025em;
}
.section-desc {
  color: var(--text-muted);
  max-width: 600px;
  margin: 1rem auto 0;
}

/* ─── ABOUT ─────────────────────────────────────────────── */
.about-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}
.about-card {
  padding: 2rem;
  border-radius: var(--radius-lg);
  transition: all var(--transition);
}
.about-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-4px);
}
.about-icon { font-size: 2rem; margin-bottom: 1rem; }
.about-card h3 { font-size: 1.15rem; font-weight: 700; margin-bottom: .75rem; }
.about-card p { color: var(--text-muted); font-size: .92rem; }
.about-card p + p { margin-top: .5rem; }
.about-card strong { color: var(--text); }
.addr { font-size: .82rem !important; color: var(--text-faint) !important; margin-top: .75rem !important; font-style: italic; }
.email-link {
  display: inline-block;
  margin-top: .75rem;
  color: var(--accent-light);
  text-decoration: none;
  font-size: .88rem;
  font-family: 'JetBrains Mono', monospace;
}
.email-link:hover { text-decoration: underline; }

/* ─── RESEARCH ──────────────────────────────────────────── */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 1.25rem;
}
.research-card {
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: 0 2px 12px rgba(99,102,241,0.07);
  padding: 1.75rem;
  position: relative;
  overflow: hidden;
  transition: all var(--transition);
  cursor: default;
}
.research-card::before {
  content: attr(data-index);
  position: absolute;
  top: 1.5rem; right: 1.75rem;
  font-size: 3rem;
  font-weight: 900;
  color: rgba(99,102,241,.07);
  font-family: 'JetBrains Mono', monospace;
  line-height: 1;
}
.research-card:hover {
  border-color: var(--accent);
  transform: translateY(-5px);
  box-shadow: 0 20px 60px rgba(99,102,241,.15);
}
.rc-icon { font-size: 1.8rem; margin-bottom: 1rem; }
.research-card h3 { font-size: 1rem; font-weight: 700; margin-bottom: .6rem; line-height: 1.4; }
.research-card p { font-size: .88rem; color: var(--text-muted); line-height: 1.65; }
.rc-tags { display: flex; flex-wrap: wrap; gap: .4rem; margin-top: 1.1rem; }
.rc-tags span {
  padding: .2rem .65rem;
  background: rgba(99,102,241,.08);
  border: 1px solid rgba(99,102,241,.25);
  border-radius: 999px;
  font-size: .72rem;
  color: #4338ca;
  font-weight: 600;
}

/* ─── PUBLICATIONS ──────────────────────────────────────── */
.pub-filters {
  display: flex;
  gap: .6rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 2.5rem;
}
.pub-filter {
  padding: .45rem 1.25rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-muted);
  font-size: .85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  font-family: 'Inter', sans-serif;
}
.pub-filter:hover, .pub-filter.active {
  border-color: var(--accent);
  background: rgba(99,102,241,.12);
  color: var(--accent-light);
}
.pub-list { display: flex; flex-direction: column; gap: 1rem; }
.pub-item {
  display: flex;
  gap: 1.25rem;
  padding: 1.5rem;
  background: #ffffff;
  border: 1px solid var(--border);
  box-shadow: 0 1px 8px rgba(99,102,241,0.06);
  border-radius: var(--radius-lg);
  transition: all var(--transition);
}
.pub-item:hover {
  border-color: var(--border-hover);
  background: var(--surface-hover);
}
.pub-item.hidden { display: none; }
.pub-year-badge {
  flex-shrink: 0;
  width: 56px; height: 56px;
  background: linear-gradient(135deg, rgba(99,102,241,.2), rgba(14,165,233,.2));
  border: 1px solid rgba(99,102,241,.3);
  border-radius: 12px;
  display: grid;
  place-items: center;
  font-size: .75rem;
  font-weight: 800;
  color: var(--accent-light);
  font-family: 'JetBrains Mono', monospace;
  line-height: 1.2;
  text-align: center;
}
.pub-body { flex: 1; min-width: 0; }
.pub-venue { margin-bottom: .4rem; }
.venue-tag {
  display: inline-block;
  padding: .15rem .6rem;
  border-radius: 6px;
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
}
.venue-tag.journal { background: rgba(22,163,74,.1); color: #15803d; border: 1px solid rgba(22,163,74,.3); }
.venue-tag.conf    { background: rgba(2,132,199,.1); color: #0369a1; border: 1px solid rgba(2,132,199,.3); }
.pub-title {
  font-size: .97rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: .4rem;
  color: var(--text);
}
.pub-authors { font-size: .82rem; color: var(--text-muted); margin-bottom: .25rem; }
.pub-conf { font-size: .8rem; color: var(--text-faint); font-style: italic; }
.pub-link {
  display: inline-block;
  margin-top: .5rem;
  color: var(--accent-light);
  font-size: .8rem;
  font-weight: 600;
  text-decoration: none;
  transition: color var(--transition);
}
.pub-link:hover { color: var(--accent-2); text-decoration: underline; }

/* ─── TEAM ──────────────────────────────────────────────── */
.team-group { margin-bottom: 3.5rem; }
.team-group:last-child { margin-bottom: 0; }
.team-group-title {
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .12em;
  color: var(--accent-light);
  margin-bottom: 1.25rem;
  padding-bottom: .6rem;
  border-bottom: 1px solid var(--border);
}
.team-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 1rem;
}
.team-grid-1 { grid-template-columns: minmax(280px, 420px); }
.team-card {
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  gap: 1rem;
  transition: all var(--transition);
}
.team-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-3px);
}
.team-lead { padding: 1.75rem; }
.team-avatar {
  width: 46px; height: 46px;
  flex-shrink: 0;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), var(--accent-3));
  display: grid;
  place-items: center;
  font-weight: 800;
  font-size: .8rem;
  color: #fff;
  font-family: 'JetBrains Mono', monospace;
}
.team-avatar-lead {
  width: 72px; height: 72px;
  border-radius: 16px;
  font-size: 1rem;
  padding: 0;
  overflow: hidden;
}
.avatar-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
  display: block;
}
.team-info h4 { font-size: .95rem; font-weight: 700; line-height: 1.2; }
.team-info .team-role {
  display: inline-block;
  padding: .15rem .6rem;
  border-radius: 6px;
  font-size: .7rem;
  font-weight: 600;
  margin-top: .3rem;
}
.team-role.pi       { background: rgba(147,51,234,.1); color: #7e22ce; border: 1px solid rgba(147,51,234,.3); }
.team-role.postdoc  { background: rgba(2,132,199,.1);  color: #0369a1; border: 1px solid rgba(2,132,199,.3); }
.team-role.phd      { background: rgba(99,102,241,.1); color: #4338ca; border: 1px solid rgba(99,102,241,.3); }
.team-role.mtech    { background: rgba(22,163,74,.1);  color: #15803d; border: 1px solid rgba(22,163,74,.25); }
.team-dept { font-size: .78rem; color: var(--text-muted); margin-top: .35rem; line-height: 1.4; }
.team-email {
  display: block;
  font-size: .75rem;
  color: var(--accent-light);
  text-decoration: none;
  font-family: 'JetBrains Mono', monospace;
  margin-top: .35rem;
}
.team-email:hover { text-decoration: underline; }

/* ─── CONTACT ───────────────────────────────────────────── */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}
.contact-card {
  padding: 2rem;
  border-radius: var(--radius-lg);
  transition: all var(--transition);
}
.contact-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-4px);
}
.contact-icon { font-size: 2rem; margin-bottom: 1rem; }
.contact-card h3 { font-weight: 700; margin-bottom: .75rem; }
.contact-card p { color: var(--text-muted); font-size: .9rem; line-height: 1.7; }

/* ─── MAP LINK ──────────────────────────────────────────── */
.map-link {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  margin-top: 1rem;
  padding: .45rem 1rem;
  border-radius: 999px;
  border: 1px solid rgba(99,102,241,.35);
  background: rgba(99,102,241,.08);
  color: var(--accent-light);
  font-size: .82rem;
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition);
}
.map-link:hover {
  background: rgba(99,102,241,.18);
  border-color: var(--accent);
  transform: translateY(-1px);
}

/* ─── IITK LOGO ─────────────────────────────────────────── */
.iitk-logo {
  width: 100%;
  max-width: 200px;
  height: auto;
  object-fit: contain;
  filter: none;
  opacity: .9;
  margin-bottom: 1rem;
  display: block;
}

/* ─── PI PHOTO ──────────────────────────────────────────── */
.pi-photo-wrap {
  flex-shrink: 0;
  width: 90px; height: 90px;
  border-radius: 18px;
  overflow: hidden;
  border: 2px solid rgba(168,85,247,.4);
  box-shadow: 0 0 24px rgba(168,85,247,.25);
}
.pi-photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
  display: block;
}

/* ─── FOOTER ────────────────────────────────────────────── */
footer {
  background: #ffffff;
  border-top: 1px solid var(--border);
  padding: 3rem 0 2rem;
}
.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
  text-align: center;
}
.footer-brand { display: flex; align-items: center; gap: .75rem; }
.footer-links { display: flex; gap: 2rem; flex-wrap: wrap; justify-content: center; }
.footer-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: .85rem;
  transition: color var(--transition);
}
.footer-links a:hover { color: var(--text); }
.footer-copy { font-size: .78rem; color: var(--text-faint); }

/* ─── ANIMATIONS ────────────────────────────────────────── */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity .6s cubic-bezier(.4,0,.2,1), transform .6s cubic-bezier(.4,0,.2,1);
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ─── RESPONSIVE ────────────────────────────────────────── */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-toggle { display: flex; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(248,250,255,.97);
    align-items: center;
    justify-content: center;
    gap: 2rem;
    font-size: 1.3rem;
    z-index: 999;
  }
  .hero-stats { gap: 1.5rem; }
  .stat-divider { display: none; }
  .pub-item { flex-direction: column; gap: .75rem; }
  .pub-year-badge { width: 100%; height: 32px; border-radius: 8px; font-size: .7rem; }
  .team-grid-1 { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .container { padding: 0 1.25rem; }
  .section { padding: 4rem 0; }
  .hero-title { font-size: 2.8rem; }
}