/* =====================================================================
   Kshitij Ambilduke — academic homepage
   Plain HTML + CSS, no build step. All colours are tokens on :root.
   Light is the default; the toggle button sets [data-theme="dark"],
   which redefines the tokens.
   Type: the system UI font (San Francisco, Segoe UI, Roboto); Noto Sans Devanagari for the greeting.
   ===================================================================== */

:root {
  --bg: #fdfcfa;
  --surface: #ffffff;
  --surface-2: #f4f2ee;
  --text: #1f1f22;
  --heading: #141416;
  --text-muted: #55575c;
  --text-faint: #6b6d73;
  --border: #e6e3dd;
  --border-strong: #d1cdc5;
  --link: #1d5b87;
  --link-hover: #0f3d5e;
  --link-underline: rgba(29, 91, 135, 0.32);
  --accent: #1d5b87;
  --accent-soft: #edf3f8;
  --paper: #ffffff;               /* backing for figures, many have transparent backgrounds */
  --img-filter: none;
  --header-bg: rgba(253, 252, 250, 0.9);
  --show-moon: inline-block;
  --show-sun: none;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans Devanagari", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;

  --maxw: 900px;
  --gutter: 24px;
  --radius: 8px;
  --header-h: 60px;
  color-scheme: light;
}

:root[data-theme="dark"] {
  --bg: #141517;
  --surface: #1a1b1e;
  --surface-2: #212225;
  --text: #e4e2de;
  --heading: #f3f1ed;
  --text-muted: #aba8a2;
  --text-faint: #8f8c86;
  --border: #2c2d31;
  --border-strong: #3e3f43;
  --link: #b3cbe0;
  --link-hover: #dce8f3;
  --link-underline: rgba(179, 203, 224, 0.38);
  --accent: #a3bfd8;
  --accent-soft: #1c2229;
  --paper: #eceae6;
  --img-filter: brightness(0.94);
  --header-bg: rgba(20, 21, 23, 0.88);
  --show-moon: none;
  --show-sun: inline-block;
  color-scheme: dark;
}

/* ---------- Base ---------- */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 24px);
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

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

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

/* Links inside running text carry a quiet underline so they read as links in both themes. */
.prose a {
  text-decoration: underline;
  text-decoration-color: var(--link-underline);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}
.prose a:hover { text-decoration-color: currentColor; }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 3px; }

strong { font-weight: 600; }

h1, h2, h3 { color: var(--heading); font-weight: 600; }

.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.icon {
  width: 1em;
  height: 1em;
  flex: none;
  fill: currentColor;
  vertical-align: -0.125em;
}

.skip-link {
  position: absolute;
  top: -48px;
  left: 16px;
  z-index: 100;
  padding: 8px 14px;
  border-radius: 6px;
  background: var(--heading);
  color: var(--bg);
  font-family: var(--font-sans);
  font-weight: 500;
}
.skip-link:focus { top: 12px; color: var(--bg); }

/* ---------- Header / navigation ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--header-bg);
  -webkit-backdrop-filter: saturate(160%) blur(10px);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  gap: 20px;
  min-height: var(--header-h);
}

.nav-name {
  color: var(--heading);
  font-size: 1.1rem;
  font-weight: 600;
  white-space: nowrap;
}
.nav-name:hover { color: var(--heading); }

.nav-links {
  display: flex;
  gap: 2px;
  margin: 0 0 0 auto;
  padding: 0;
  list-style: none;
  font-family: var(--font-sans);
}

.nav-links a {
  display: block;
  padding: 5px 10px;
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 400;
  white-space: nowrap;
}
.nav-links a:hover { background: var(--surface-2); color: var(--heading); }

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: transparent;
  color: var(--text-muted);
  font-size: 0.95rem;
  cursor: pointer;
}
.theme-toggle:hover { border-color: var(--border-strong); color: var(--heading); }
.theme-toggle .icon-moon { display: var(--show-moon); }
.theme-toggle .icon-sun { display: var(--show-sun); }

/* ---------- Layout ---------- */

main { padding: 56px 0 0; }

.section { margin-top: 72px; }

.section-title {
  margin: 0 0 18px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  font-size: 1.4rem;
  line-height: 1.25;
  letter-spacing: -0.005em;
}

/* Small buttons: publication links, BibTeX, project links */
.links {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
}

.btn {
  display: inline-flex;
  align-items: center;
  padding: 1px 9px;
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  background: transparent;
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  line-height: 1.7;
  text-transform: uppercase;
  cursor: pointer;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn[aria-expanded="true"] { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); }

/* ---------- About ---------- */

.about {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 216px;
  grid-template-areas:
    "head profile"
    "bio  profile";
  column-gap: 56px;
  align-items: start;
}

.intro-head { grid-area: head; }
.bio { grid-area: bio; }
.profile { grid-area: profile; }

.hero-name {
  margin: 0;
  font-size: clamp(2rem, 1.5rem + 1.8vw, 2.5rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
}

.bio .greeting {
  margin: 32px 0 12px;
  color: var(--accent);
  font-size: 1.35rem;
  font-weight: 600;
  line-height: 1.3;
}

.bio p { margin: 0 0 1em; }
.bio p:last-child { margin-bottom: 0; }

.profile {
  display: grid;
  grid-template-areas: "photo" "cv" "heading" "contact";
  padding-top: 6px;
}

.profile-photo {
  grid-area: photo;
  width: 100%;
  aspect-ratio: 661 / 720;
  object-fit: cover;
  border-radius: var(--radius);
}

.btn-cv {
  grid-area: cv;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 14px;
  padding: 7px 14px;
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  color: var(--heading);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 500;
}
.btn-cv:hover { border-color: var(--accent); color: var(--accent); }
.btn-cv .icon { color: var(--text-muted); }
.btn-cv:hover .icon { color: inherit; }

.profile-heading {
  grid-area: heading;
  margin: 24px 0 8px;
  font-size: 1.1rem;
}

.contact {
  grid-area: contact;
  display: grid;
  gap: 5px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-sans);
  font-size: 0.95rem;
}

.contact a {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 400;
  overflow-wrap: anywhere;
}
.contact .icon { width: 1.05em; height: 1.05em; color: var(--text-faint); }

/* ---------- News ---------- */

.news { margin: 0; padding: 0; list-style: none; }

.news li {
  display: grid;
  grid-template-columns: 5.75rem minmax(0, 1fr);
  gap: 18px;
  padding: 8px 0;
}
.news li + li,
.news-more .news li:first-child { border-top: 1px solid var(--border); }

.news time {
  padding-top: 0.22em;
  color: var(--text-faint);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.news p { margin: 0; }

.news-more summary {
  display: inline-block;
  margin-top: 6px;
  padding: 4px 0;
  color: var(--link);
  font-family: var(--font-sans);
  font-size: 0.92rem;
  font-weight: 500;
  list-style: none;
  cursor: pointer;
}
.news-more summary::-webkit-details-marker { display: none; }
.news-more summary:hover { color: var(--link-hover); }
.news-more .when-open,
.news-more[open] .when-closed { display: none; }
.news-more[open] .when-open { display: inline; }

/* ---------- Publications ---------- */

.pubs {
  display: grid;
  gap: 36px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.pub {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: 26px;
  align-items: start;
}

.pub-thumb {
  display: flex;
  align-items: center;
  justify-content: center;
  aspect-ratio: 16 / 9;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--paper);
}
.pub-thumb img { width: 100%; height: 100%; object-fit: contain; filter: var(--img-filter); }

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1.4;
  text-transform: uppercase;
}

.pub-title {
  margin: 0 0 6px;
  font-size: 1.05rem;
  line-height: 1.38;
}
.pub-title a { color: var(--heading); }
.pub-title a:hover { color: var(--link); }

.pub-authors, .pub-venue {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.55;
}
.pub-authors strong { color: var(--heading); }
.pub-venue { margin-top: 2px; font-style: italic; }

.bibtex { position: relative; margin-top: 12px; }
.bibtex pre {
  margin: 0;
  padding: 14px 72px 14px 16px;
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--surface-2);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  line-height: 1.6;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
.copy-btn { position: absolute; top: 8px; right: 8px; background: var(--surface); }

/* ---------- Projects ---------- */

.projects {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 250px), 1fr));
  gap: 18px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.project-card {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  transition: border-color 0.15s ease;
}
.project-card:hover { border-color: var(--border-strong); }

.project-media {
  display: block;
  aspect-ratio: 16 / 10;
  padding: 12px;
  border-bottom: 1px solid var(--border);
  background: var(--paper);
}
.project-media img { width: 100%; height: 100%; object-fit: contain; filter: var(--img-filter); }

.project-body {
  display: flex;
  flex: 1;
  flex-direction: column;
  gap: 8px;
  padding: 12px 14px 14px;
}

.project-name {
  margin: 0;
  font-size: 1.02rem;
  line-height: 1.38;
}
.project-name a { color: var(--heading); }
.project-name a:hover { color: var(--link); }
.project-card:hover .project-name a { color: var(--link); }

.card-links {
  display: flex;
  flex-wrap: wrap;
  gap: 2px 14px;
  margin: auto 0 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 500;
}
.card-links a { color: var(--text-muted); }
.card-links a:hover { color: var(--link); }

/* ---------- Notes (Jibber-Jabber) ---------- */

.soon {
  display: inline-block;
  margin-left: 10px;
  padding: 1px 9px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 500;
  vertical-align: 0.3em;
}

.notes {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  align-items: start;
}

.note-group {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}

.note-group summary {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  color: var(--heading);
  font-family: var(--font-sans);
  font-weight: 500;
  list-style: none;
  cursor: pointer;
}
.note-group summary::-webkit-details-marker { display: none; }
.note-group summary::after {
  content: "";
  width: 7px;
  height: 7px;
  margin-left: auto;
  border-right: 2px solid var(--text-faint);
  border-bottom: 2px solid var(--text-faint);
  transform: rotate(45deg) translateY(-2px);
  transition: transform 0.15s ease;
}
.note-group[open] summary::after { transform: rotate(-135deg) translateY(-2px); }
.note-group[open] summary { border-bottom: 1px solid var(--border); }

.note-count {
  padding: 0 7px;
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 500;
}

.note-list {
  margin: 0;
  padding: 12px 16px 16px 36px;
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.8;
}

/* ---------- Footer ---------- */

.site-footer {
  margin-top: 96px;
  padding: 22px 0 40px;
  border-top: 1px solid var(--border);
  color: var(--text-faint);
  font-family: var(--font-sans);
  font-size: 0.9rem;
}
.site-footer .container {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.site-footer p { margin: 0; }
.footer-links { display: flex; gap: 16px; margin: 0; padding: 0; list-style: none; }
.footer-links a { color: var(--text-faint); font-size: 1.05rem; }
.footer-links a:hover { color: var(--link); }

/* ---------- Project pages ---------- */

.project-page { max-width: 800px; }

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 20px;
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 400;
}
.back-link:hover { color: var(--link); }

.project-title {
  margin: 0;
  font-size: clamp(1.8rem, 1.3rem + 2vw, 2.4rem);
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.project-cover {
  margin: 28px 0;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--paper);
}
.project-cover img { width: auto; max-height: 420px; margin: 0 auto; filter: var(--img-filter); }

.summary {
  margin: 0 0 24px;
  padding: 2px 0 2px 22px;
  border-left: 3px solid var(--accent);
}
.summary p { margin: 0; }
.summary ul { margin: 10px 0 0; padding-left: 1.3em; }

.prose p { margin: 0 0 1em; }
.prose p:last-child { margin-bottom: 0; }

.doc-section { margin-top: 44px; }
.doc-section h2 { margin: 0; font-size: 1.35rem; }
.doc-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}
.doc-section > h2 { margin-bottom: 12px; }

.embed {
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--surface-2);
}
.embed iframe { display: block; width: 100%; height: auto; border: 0; }
.embed--landscape iframe { aspect-ratio: 4 / 3; }
.embed--slides iframe { aspect-ratio: 16 / 10.5; }
.embed--doc iframe { height: min(88vh, 1100px); }
.embed--video iframe { aspect-ratio: 16 / 9; }

.project-pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 64px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
}
.project-pager a {
  display: block;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--heading);
  font-weight: 500;
  line-height: 1.4;
}
.project-pager a:hover { border-color: var(--border-strong); color: var(--link); }
.project-pager span {
  display: block;
  color: var(--text-faint);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.project-pager .next { grid-column: 2; text-align: right; }

/* ---------- Responsive ---------- */

@media (max-width: 760px) {
  :root { --gutter: 16px; --header-h: 96px; }

  main { padding-top: 32px; }
  .section { margin-top: 56px; }

  .nav { flex-wrap: wrap; gap: 0 12px; padding-top: 10px; }
  .nav-name { flex: 1; }
  .theme-toggle { order: 2; }
  .nav-links {
    order: 3;
    width: calc(100% + 20px);
    margin: 4px -10px 0;
    padding-bottom: 6px;
    overflow-x: auto;
    scrollbar-width: none;
  }
  .nav-links::-webkit-scrollbar { display: none; }

  .about {
    grid-template-columns: minmax(0, 1fr);
    grid-template-areas: "head" "profile" "bio";
  }
  .profile {
    grid-template-columns: 116px minmax(0, 1fr);
    grid-template-areas:
      "photo heading"
      "photo contact"
      "photo cv";
    column-gap: 18px;
    align-items: start;
    margin-top: 24px;
    padding-top: 0;
  }
  .profile-heading { margin-top: 0; }
  .btn-cv { justify-self: start; margin-top: 12px; padding: 4px 12px; font-size: 0.9rem; }
  .contact { font-size: 0.92rem; }
  .bio .greeting { margin-top: 28px; }

  .pub { grid-template-columns: minmax(0, 1fr); gap: 12px; }
  .pub-thumb { max-width: 360px; }

  .notes { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 520px) {
  .news li { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .project-pager { grid-template-columns: minmax(0, 1fr); }
  .project-pager .next { grid-column: 1; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .project-card, .note-group summary::after { transition: none; }
}

@media print {
  .site-header, .theme-toggle, .site-footer, .project-pager, .embed, .links { display: none; }
  body { background: #fff; color: #000; }
  main { padding-top: 0; }
}