/* ============================================================
   Chandrachud Pati — research portfolio
   Palette: warm paper + ink, with a quantum-indigo accent
   ============================================================ */

:root {
  --paper: #fbfaf6;
  --paper-2: #f3f1ea;
  --ink: #1b1a17;
  --ink-soft: #4a4843;
  --ink-faint: #8a877e;
  --line: #e3e0d6;
  --accent: #2f4b6e;        /* deep slate-indigo */
  --accent-2: #6b5b95;      /* quantum violet */
  --accent-soft: #eaeef4;
  --card: #ffffff;
  --shadow: 0 1px 2px rgba(27,26,23,.04), 0 8px 28px rgba(27,26,23,.06);
  --max: 980px;
  --serif: "Newsreader", Georgia, "Times New Roman", serif;
  --sans: "Inter", system-ui, -apple-system, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;
}

html[data-theme="dark"] {
  --paper: #14151a;
  --paper-2: #1b1d24;
  --ink: #ecebe6;
  --ink-soft: #b9b7b0;
  --ink-faint: #807e78;
  --line: #2a2c34;
  --accent: #8fb3df;
  --accent-2: #a99bd0;
  --accent-soft: #20242e;
  --card: #1a1c22;
  --shadow: 0 1px 2px rgba(0,0,0,.3), 0 10px 30px rgba(0,0,0,.35);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 84px; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  transition: background .35s ease, color .35s ease;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

.skip-link {
  position: absolute; left: -999px; top: 0;
  background: var(--ink); color: var(--paper); padding: 10px 16px; z-index: 100;
}
.skip-link:focus { left: 12px; top: 12px; }

/* ---------- NAV ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--paper) 82%, transparent);
  backdrop-filter: saturate(140%) blur(10px);
  border-bottom: 1px solid transparent;
  transition: border-color .3s ease, background .3s ease;
}
.nav.scrolled { border-bottom-color: var(--line); }
.nav-inner {
  max-width: var(--max); margin: 0 auto; padding: 14px 24px;
  display: flex; align-items: center; gap: 24px;
}
.nav-brand {
  font-family: var(--serif); font-weight: 600; font-size: 1.15rem;
  letter-spacing: .3px; color: var(--ink);
}
.nav-brand:hover { text-decoration: none; color: var(--accent); }
.nav-links { margin-left: auto; display: flex; gap: 22px; }
.nav-links a {
  color: var(--ink-soft); font-size: .9rem; font-weight: 500;
  letter-spacing: .2px; position: relative;
}
.nav-links a:hover { color: var(--ink); text-decoration: none; }
.nav-links a::after {
  content: ""; position: absolute; left: 0; bottom: -6px; height: 2px; width: 0;
  background: var(--accent); transition: width .25s ease;
}
.nav-links a:hover::after { width: 100%; }
.nav-links a.tab-link { cursor: pointer; }
.nav-links a.active { color: var(--ink); font-weight: 600; }
.nav-links a.active::after { width: 100%; }
.theme-toggle {
  background: none; border: 1px solid var(--line); color: var(--ink-soft);
  width: 36px; height: 36px; border-radius: 50%; cursor: pointer;
  display: grid; place-items: center; font-size: 1rem; transition: all .2s ease;
}
.theme-toggle:hover { border-color: var(--accent); color: var(--accent); transform: rotate(20deg); }

/* ---------- HERO ---------- */
.hero { max-width: var(--max); margin: 0 auto; padding: 72px 24px 56px; }
.hero-grid {
  display: grid; grid-template-columns: 1.6fr 1fr; gap: 56px; align-items: center;
}
.eyebrow {
  font-family: var(--mono); font-size: .78rem; letter-spacing: 1.5px;
  text-transform: uppercase; color: var(--accent-2); margin: 0 0 14px;
}
.hero h1 {
  font-family: var(--serif); font-weight: 500;
  font-size: clamp(2.6rem, 6vw, 4.1rem); line-height: 1.04;
  margin: 0 0 20px; letter-spacing: -.5px;
}
.lede { font-size: 1.18rem; color: var(--ink-soft); margin: 0 0 28px; max-width: 36ch; }
.lede em { font-style: italic; color: var(--ink); }
.lede strong { color: var(--ink); font-weight: 600; }

.hero-cta { display: flex; gap: 14px; margin-bottom: 26px; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: 11px 22px; border-radius: 999px;
  font-size: .92rem; font-weight: 500; transition: all .2s ease;
}
.btn:hover { text-decoration: none; transform: translateY(-2px); }
.btn-primary { background: var(--accent); color: #fff; }
html[data-theme="dark"] .btn-primary { color: #11131a; }
.btn-primary:hover { box-shadow: var(--shadow); }
.btn-ghost { border: 1px solid var(--line); color: var(--ink); }
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

.hero-links {
  list-style: none; margin: 0; padding: 0; display: flex; gap: 20px; flex-wrap: wrap;
  font-size: .9rem;
}
.hero-links a { color: var(--ink-soft); font-weight: 500; }
.hero-links a:hover { color: var(--accent); }

.hero-photo { display: flex; flex-direction: column; align-items: center; gap: 28px; }
.photo-frame {
  position: relative; width: 280px; height: 280px; border-radius: 50%;
  padding: 6px; background:
    conic-gradient(from 200deg, var(--accent), var(--accent-2), var(--accent));
  box-shadow: var(--shadow);
}
.photo-frame img {
  width: 100%; height: 100%; border-radius: 50%; object-fit: cover;
  image-rendering: auto; background: var(--paper-2);
  border: 4px solid var(--paper);
}
.quick-facts { margin: 0; width: 100%; max-width: 220px; }
.quick-facts > div {
  display: flex; justify-content: space-between; gap: 12px;
  padding: 8px 0; border-bottom: 1px solid var(--line); font-size: .85rem;
}
.quick-facts dt { color: var(--ink-faint); margin: 0; }
.quick-facts dd { margin: 0; color: var(--ink); font-weight: 500; text-align: right; }

/* ---------- SECTIONS ---------- */
.section { max-width: var(--max); margin: 0 auto; padding: 56px 24px; }
.section-head { display: flex; align-items: baseline; gap: 16px; margin-bottom: 36px; }
.sec-num {
  font-family: var(--mono); font-size: .8rem; color: var(--accent-2);
  letter-spacing: 1px;
}
.section-head h2 {
  font-family: var(--serif); font-weight: 500; font-size: 2rem; margin: 0;
  letter-spacing: -.3px;
}
.section-head::after {
  content: ""; flex: 1; height: 1px; background: var(--line); align-self: center;
}

.prose p { margin: 0 0 18px; color: var(--ink-soft); max-width: 70ch; }
.prose strong { color: var(--ink); font-weight: 600; }

/* ---------- RESEARCH CARDS ---------- */
.research-intro {
  font-family: var(--serif); font-size: 1.3rem; line-height: 1.5;
  color: var(--ink); margin: -8px 0 28px; max-width: 60ch;
}
.research-intro em { font-style: italic; color: var(--accent-2); }
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: 14px;
  padding: 24px 22px; transition: transform .2s ease, box-shadow .2s ease, border-color .2s ease;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow); border-color: transparent; }
.card h3 {
  font-family: var(--serif); font-weight: 600; font-size: 1.12rem; margin: 0 0 10px;
  color: var(--ink);
}
.card p { margin: 0; font-size: .92rem; color: var(--ink-soft); line-height: 1.55; }

/* ---------- PUBLICATIONS ---------- */
.pub-list { list-style: none; margin: 0; padding: 0; }
.pub {
  display: grid; grid-template-columns: 70px 1fr; gap: 22px;
  padding: 24px 0; border-top: 1px solid var(--line);
}
.pub:last-child { border-bottom: 1px solid var(--line); }
.pub-year { font-family: var(--mono); color: var(--accent-2); font-size: .9rem; padding-top: 4px; }
.pub-body h3 {
  font-family: var(--serif); font-weight: 600; font-size: 1.2rem; margin: 0 0 6px;
  line-height: 1.35;
}
.pub-authors { margin: 0 0 8px; color: var(--ink-soft); font-size: .92rem; }
.pub-venue { margin: 0 0 8px; color: var(--ink-soft); font-size: .92rem; }
.pub-links { margin: 0; font-size: .88rem; font-family: var(--mono); }
.tag {
  display: inline-block; font-family: var(--sans); font-size: .72rem; font-weight: 600;
  letter-spacing: .4px; text-transform: uppercase; padding: 2px 9px; border-radius: 6px;
  background: var(--accent-soft); color: var(--accent); margin-right: 8px;
  vertical-align: middle;
}
.pub-anon h3 { font-style: italic; font-weight: 500; color: var(--ink-soft); }
.tag-review { background: #fbeede; color: #9a6a16; }
.tag-accepted { background: #e2f2e6; color: #2f7d43; }
html[data-theme="dark"] .tag-accepted { background: #1c3325; color: #74c98a; }
html[data-theme="dark"] .tag-review { background: #3a2e16; color: #d9ab57; }

/* ---------- PROJECTS ---------- */
.proj-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.proj {
  display: block; background: var(--card); border: 1px solid var(--line);
  border-radius: 14px; padding: 22px; color: inherit;
  transition: transform .2s ease, box-shadow .2s ease, border-color .2s ease;
}
.proj:hover { text-decoration: none; transform: translateY(-4px); box-shadow: var(--shadow); border-color: transparent; }
.proj-top { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 10px; }
.proj-top h3 { font-family: var(--mono); font-weight: 500; font-size: 1.02rem; margin: 0; color: var(--ink); }
.proj-lang {
  font-size: .72rem; font-family: var(--sans); font-weight: 600; color: var(--accent-2);
  background: var(--accent-soft); padding: 2px 9px; border-radius: 6px; white-space: nowrap;
}
.proj p { margin: 0 0 14px; font-size: .92rem; color: var(--ink-soft); }
.proj code, .prose code {
  font-family: var(--mono); font-size: .82em; padding: 1px 6px; border-radius: 5px;
  background: var(--accent-soft); color: var(--accent-2);
}
.proj-arrow { font-size: .84rem; color: var(--accent); font-weight: 500; }
.proj-more { margin: 22px 0 0; font-size: .92rem; font-weight: 500; }

/* ---------- TIMELINE ---------- */
.timeline { position: relative; padding-left: 26px; }
.timeline::before {
  content: ""; position: absolute; left: 6px; top: 6px; bottom: 6px; width: 2px;
  background: var(--line);
}
.tl-item { position: relative; padding-bottom: 30px; }
.tl-item:last-child { padding-bottom: 0; }
.tl-item::before {
  content: ""; position: absolute; left: -26px; top: 7px; width: 10px; height: 10px;
  border-radius: 50%; background: var(--accent); border: 2px solid var(--paper);
}
.tl-date { font-family: var(--mono); font-size: .8rem; color: var(--ink-faint); margin-bottom: 4px; }
.tl-body h3 { font-family: var(--serif); font-weight: 600; font-size: 1.12rem; margin: 0 0 3px; }
.tl-org { margin: 0 0 8px; font-size: .9rem; color: var(--accent-2); font-weight: 500; }
.tl-body p:last-child { margin: 0; font-size: .92rem; color: var(--ink-soft); max-width: 64ch; }

/* ---------- AWARDS ---------- */
.awards { list-style: none; margin: 0; padding: 0; display: grid; gap: 4px; }
.awards li {
  display: flex; gap: 14px; align-items: flex-start; padding: 14px 4px;
  border-bottom: 1px solid var(--line); font-size: .96rem;
}
.award-mark { color: var(--accent-2); font-size: .9rem; padding-top: 3px; }
.awards strong { color: var(--ink); font-weight: 600; }
.awards div { color: var(--ink-soft); }

/* ---------- CONTACT ---------- */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: start; }
.contact-lede { font-family: var(--serif); font-size: 1.35rem; line-height: 1.5; margin: 0; color: var(--ink); }
.contact-list { list-style: none; margin: 0; padding: 0; }
.contact-list li {
  display: flex; gap: 16px; padding: 11px 0; border-bottom: 1px solid var(--line);
  font-size: .95rem;
}
.contact-list span {
  font-family: var(--mono); font-size: .78rem; text-transform: uppercase;
  letter-spacing: .5px; color: var(--ink-faint); width: 78px; flex-shrink: 0; padding-top: 2px;
}

/* ---------- GALLERY (masonry, native aspect ratios) ---------- */
.gallery {
  column-count: 2;
  column-gap: 14px;
  max-width: 70ch;        /* stay within the text-content column */
}
@media (max-width: 520px) { .gallery { column-count: 1; } }

.gallery figure {
  break-inside: avoid;
  margin: 0 0 14px;
  position: relative;
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  cursor: zoom-in;
  background: var(--paper-2);
}
.gallery img {
  display: block;
  width: 100%;
  height: auto;           /* keeps each photo's true resolution/aspect */
  transition: transform .5s ease;
}
.gallery figure:hover img { transform: scale(1.04); }
.gallery figcaption {
  position: absolute; left: 0; right: 0; bottom: 0;
  padding: 20px 14px 12px;
  font-size: .82rem; font-weight: 500; color: #fff;
  background: linear-gradient(to top, rgba(0,0,0,.72), rgba(0,0,0,0));
  opacity: 0; transform: translateY(6px);
  transition: opacity .25s ease, transform .25s ease;
}
.gallery figure:hover figcaption { opacity: 1; transform: none; }

/* ---------- LIGHTBOX ---------- */
.lightbox {
  position: fixed; inset: 0; z-index: 200;
  display: none; place-items: center;
  background: rgba(12,12,14,.86);
  backdrop-filter: blur(4px);
  padding: 24px;
  cursor: zoom-out;
}
.lightbox.open { display: grid; }
.lightbox img {
  max-width: 92vw; max-height: 88vh;
  border-radius: 10px; box-shadow: 0 20px 60px rgba(0,0,0,.5);
}
.lightbox-close {
  position: absolute; top: 18px; right: 24px;
  background: none; border: none; color: #fff; font-size: 2.2rem; line-height: 1;
  cursor: pointer; opacity: .8; transition: opacity .2s ease;
}
.lightbox-close:hover { opacity: 1; }

/* ---------- FOOTER ---------- */
.footer {
  max-width: var(--max); margin: 0 auto; padding: 40px 24px 60px;
  border-top: 1px solid var(--line); text-align: center; color: var(--ink-faint);
  font-size: .85rem;
}
.footer p { margin: 4px 0; }
.footer-note { font-family: var(--mono); font-size: .76rem; }

/* ---------- REVEAL ANIMATION ---------- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .6s ease, transform .6s ease; }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

/* ---------- RESPONSIVE ---------- */
@media (max-width: 820px) {
  .hero-grid { grid-template-columns: 1fr; gap: 40px; }
  .hero-photo { order: -1; flex-direction: row; flex-wrap: wrap; justify-content: flex-start; }
  .quick-facts { max-width: 280px; }
  .cards { grid-template-columns: 1fr 1fr; }
  /* tabs move to a scrollable strip below the brand */
  .nav-inner { flex-wrap: wrap; row-gap: 10px; }
  .nav-links {
    order: 3; width: 100%; margin-left: 0; gap: 20px;
    overflow-x: auto; -webkit-overflow-scrolling: touch;
    padding-bottom: 2px; scrollbar-width: none;
  }
  .nav-links::-webkit-scrollbar { display: none; }
  .nav-links a { white-space: nowrap; }
}
@media (max-width: 560px) {
  body { font-size: 16px; }
  .cards, .proj-grid, .contact-grid { grid-template-columns: 1fr; }
  .hero { padding-top: 48px; }
  .pub { grid-template-columns: 1fr; gap: 6px; }
  .pub-year { padding-top: 0; }
  .contact-lede { font-size: 1.15rem; }
}