/* ==========================================================================
   Siva Sai - personal academic site
   Tokens: one accent (petrol teal), one radius (3px), cool-neutral greys.
   Type: Newsreader (headings, publication titles) + Geist (UI, body).
   ========================================================================== */

:root {
  /* light theme */
  --paper:        #FAFAF8;
  --paper-2:      #F1F2EE;
  --paper-3:      #FFFFFF;
  --ink:          #16191C;
  --ink-2:        #565C61;
  --ink-3:        #666C71; /* darkened to clear WCAG AA on both paper tones */
  --rule:         #DEE0DC;
  --rule-strong:  #C3C7C2;
  --accent:       #14524E;
  --accent-hover: #0C3A37;
  --accent-soft:  #E3EDEA;
  --accent-line:  #9CBFB9;
  --scrim:        rgba(9, 22, 26, 0.52);

  --radius: 3px;
  --maxw: 1120px;
  --gutter: 2rem;
  --section-y: 5.5rem;

  --ff-display: "Newsreader", Georgia, "Times New Roman", serif;
  --ff-ui: "Geist", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;

  --ease: cubic-bezier(0.16, 1, 0.3, 1);

  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper:        #121513;
    --paper-2:      #191D1B;
    --paper-3:      #1D2220;
    --ink:          #ECEEEA;
    --ink-2:        #A5ACA7;
    --ink-3:        #868D89;
    --rule:         #2B302D;
    --rule-strong:  #3C433F;
    --accent:       #79C6B8;
    --accent-hover: #9BD8CC;
    --accent-soft:  #1B2B28;
    --accent-line:  #345750;
    --scrim:        rgba(6, 14, 17, 0.62);

    color-scheme: dark;
  }
}

/* --------------------------------------------------------------- reset -- */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 5.5rem;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--ff-ui);
  font-size: 1rem;
  line-height: 1.65;
  font-synthesis-weight: none;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { max-width: 100%; display: block; }
h1, h2, h3, h4 { margin: 0; font-weight: 500; }
p { margin: 0 0 1.1em; }
ul, ol { margin: 0; padding: 0; list-style: none; }

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
  transition: color 0.18s var(--ease);
}
a:hover { color: var(--accent-hover); }

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

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  z-index: 100;
  padding: 0.6rem 1rem;
  background: var(--accent);
  color: #fff;
  border-radius: var(--radius);
  font-size: 0.875rem;
  transition: top 0.2s var(--ease);
}
.skip-link:focus { top: 1rem; color: #fff; }

/* ------------------------------------------------------------- layout --- */

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

/* Sections alternate between the two paper tones; the tone change is the only
   divider they need. */
.section { padding-block: var(--section-y); }
.section--tint { background: var(--paper-2); }

.section-head {
  max-width: 52ch;
  margin-bottom: 2.75rem;
}

.section-title {
  font-family: var(--ff-display);
  font-size: clamp(1.65rem, 1.2rem + 1.6vw, 2.2rem);
  line-height: 1.15;
  letter-spacing: -0.015em;
  font-weight: 500;
}

.section-note {
  margin: 0.75rem 0 0;
  color: var(--ink-2);
  font-size: 0.975rem;
}

/* ---------------------------------------------------------------- nav --- */

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  height: 4rem;
  display: flex;
  align-items: center;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: saturate(140%) blur(10px);
  -webkit-backdrop-filter: saturate(140%) blur(10px);
  border-bottom: 1px solid var(--rule);
}

.nav__inner {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.nav__brand {
  font-family: var(--ff-display);
  font-size: 1.1rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  color: var(--ink);
  text-decoration: none;
  white-space: nowrap;
}
.nav__brand:hover { color: var(--accent); }

.nav__links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  margin-left: auto;
  /* without min-width:0 this flex child refuses to shrink below its nowrap
     content and pushes the whole page wider than the viewport */
  min-width: 0;
  font-size: 0.9rem;
}

.nav__links a {
  position: relative;
  color: var(--ink-2);
  text-decoration: none;
  padding-block: 0.35rem;
  white-space: nowrap;
}
.nav__links a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1.5px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s var(--ease);
}
.nav__links a:hover,
.nav__links a[aria-current="true"] { color: var(--ink); }
.nav__links a:hover::after,
.nav__links a[aria-current="true"]::after { transform: scaleX(1); }

.nav__cv {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.42rem 0.85rem;
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius);
  color: var(--ink) !important;
}
.nav__cv::after { display: none; }
.nav__cv:hover {
  border-color: var(--accent);
  color: var(--accent) !important;
}

/* --------------------------------------------------------------- hero --- */

.hero__band {
  position: relative;
  height: clamp(150px, 20vw, 216px);
  overflow: hidden;
  background: #0d2230;
}
.hero__band img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
}
.hero__band::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    rgba(9, 22, 26, 0.10) 0%,
    rgba(9, 22, 26, 0.30) 58%,
    var(--paper) 100%
  );
}

.hero__body {
  display: grid;
  grid-template-columns: 208px 1fr;
  gap: 2.75rem;
  align-items: start;
  padding-bottom: 4rem;
}

.hero__portrait {
  margin-top: -5.25rem;
  position: relative;
  z-index: 2;
}
.hero__portrait img {
  width: 100%;
  /* height:auto is required: the width/height attributes on the <img> map to
     presentational hints that would otherwise win over aspect-ratio. */
  height: auto;
  aspect-ratio: 4 / 5;
  object-fit: cover;
  object-position: 50% 28%;
  border-radius: var(--radius);
  border: 4px solid var(--paper);
  box-shadow: 0 14px 34px -18px rgba(12, 34, 38, 0.55);
}

.hero__contact {
  margin-top: 1.25rem;
  display: flex;
  flex-direction: column;
  /* hug the text, so the email button's underline does not span the column */
  align-items: flex-start;
  gap: 0.55rem;
  font-size: 0.875rem;
}
.hero__contact a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--ink-2);
  text-decoration: none;
}
.hero__contact a:hover { color: var(--accent); }
.hero__contact i { font-size: 1.05rem; color: var(--ink-3); }
.hero__contact a:hover i { color: var(--accent); }

/* The email starts life as a button and is swapped for a real mailto link
   once clicked; both states have to look identical. */
.reveal-mail {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0;
  border: 0;
  background: none;
  font: inherit;
  color: var(--ink-2);
  text-align: left;
  cursor: pointer;
  border-bottom: 1px dashed var(--rule-strong);
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.reveal-mail:hover { color: var(--accent); border-color: var(--accent); }
.reveal-mail i { font-size: 1.05rem; color: var(--ink-3); }
.reveal-mail:hover i { color: var(--accent); }

.hero__contact .reveal-mail { font-size: 0.875rem; }
.contact__list .reveal-mail { color: var(--accent); }

.contact__noscript { color: var(--ink-2); }

.hero__text { padding-top: 1.75rem; }

.hero__name {
  font-family: var(--ff-display);
  font-size: clamp(2.75rem, 1.7rem + 4.2vw, 4.25rem);
  line-height: 1.02;
  letter-spacing: -0.028em;
  font-weight: 450;
}

.hero__role {
  margin: 0.85rem 0 0;
  font-size: 1.05rem;
  color: var(--ink);
}
.hero__role span {
  display: block;
  color: var(--ink-2);
  font-size: 0.975rem;
}

.hero__lede {
  margin: 1.35rem 0 0;
  max-width: 54ch;
  font-size: 1.0625rem;
  color: var(--ink-2);
}

.hero__actions {
  margin-top: 1.9rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.62rem 1.1rem;
  border-radius: var(--radius);
  border: 1px solid transparent;
  font-size: 0.9rem;
  font-weight: 500;
  text-decoration: none;
  white-space: nowrap;
  transition: background 0.18s var(--ease), border-color 0.18s var(--ease),
              color 0.18s var(--ease), transform 0.1s var(--ease);
}
.btn:active { transform: translateY(1px); }

.btn--solid {
  background: var(--accent);
  color: #FCFEFD;
}
.btn--solid:hover { background: var(--accent-hover); color: #FCFEFD; }
@media (prefers-color-scheme: dark) {
  .btn--solid { color: #0E1917; }
  .btn--solid:hover { color: #0E1917; }
}

.btn--line {
  border-color: var(--rule-strong);
  color: var(--ink);
}
.btn--line:hover { border-color: var(--accent); color: var(--accent); }

/* ------------------------------------------------------------ metrics --- */

.metrics {
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  background: var(--paper-2);
}
.metrics__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}
.metrics__cell {
  padding: 1.6rem 1.25rem 1.7rem;
  border-left: 1px solid var(--rule);
}
.metrics__cell:first-child { border-left: 0; padding-left: 0; }
.metrics__value {
  font-family: var(--ff-display);
  font-size: clamp(1.9rem, 1.4rem + 1.5vw, 2.5rem);
  line-height: 1;
  letter-spacing: -0.02em;
  font-weight: 500;
  font-variant-numeric: tabular-nums;
}
.metrics__label {
  margin-top: 0.5rem;
  font-size: 0.85rem;
  color: var(--ink-2);
}
.metrics__source {
  padding: 0 0 1.5rem;
  font-size: 0.8125rem;
  color: var(--ink-3);
}

/* ----------------------------------------------------------- research --- */

.themes {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  overflow: hidden;
}
.theme {
  grid-column: span 2;
  background: var(--paper);
  padding: 1.9rem 1.7rem 2rem;
}
.theme--wide { grid-column: span 3; }
.theme--lead {
  grid-column: span 6;
  background: var(--accent-soft);
  display: grid;
  grid-template-columns: minmax(0, 0.8fr) minmax(0, 1.55fr);
  gap: 2rem;
  align-items: start;
}
.theme--lead .theme__title { font-size: 1.5rem; }

.theme__title {
  font-family: var(--ff-display);
  font-size: 1.2rem;
  line-height: 1.25;
  letter-spacing: -0.01em;
  font-weight: 500;
}
.theme__body {
  margin: 0.7rem 0 0;
  font-size: 0.95rem;
  color: var(--ink-2);
}
.theme--lead .theme__body { margin-top: 0; font-size: 1rem; color: var(--ink); }

/* --------------------------------------------------------------- bio ---- */

.bio {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(0, 1fr);
  gap: 4rem;
  align-items: start;
}
.bio__prose { font-size: 1.0625rem; max-width: 66ch; }
.bio__prose p:last-child { margin-bottom: 0; }

.aside-card {
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background: var(--paper-3);
  padding: 1.5rem 1.6rem 1.6rem;
}
.aside-card h3 {
  font-family: var(--ff-display);
  font-size: 1.1rem;
  font-weight: 500;
}
.aside-card ul { margin-top: 1rem; }
.aside-card li {
  padding-block: 0.7rem;
  border-top: 1px solid var(--rule);
  font-size: 0.925rem;
  color: var(--ink-2);
}
.aside-card li:first-child { border-top: 0; padding-top: 0; }
.aside-card strong { color: var(--ink); font-weight: 500; }

/* Each fact on its own line rather than running together as prose. */
.aside-card li > strong,
.aside-where,
.aside-note {
  display: block;
}
.aside-where { margin-top: 0.2rem; }
.aside-note {
  margin-top: 0.35rem;
  font-size: 0.9rem;
  line-height: 1.5;
}

/* ---------------------------------------------------------- timeline --- */

.timeline { display: grid; gap: 0; }

.entry {
  display: grid;
  grid-template-columns: 11rem 1fr;
  gap: 2rem;
  padding-block: 1.6rem;
  border-top: 1px solid var(--rule);
}
.entry:first-child { border-top: 0; padding-top: 0; }

.entry__when {
  font-size: 0.875rem;
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
  padding-top: 0.2rem;
}
.entry__role {
  font-family: var(--ff-display);
  font-size: 1.2rem;
  line-height: 1.3;
  font-weight: 500;
}
.entry__org {
  margin: 0.15rem 0 0;
  font-size: 0.95rem;
  color: var(--ink-2);
}
.entry__detail {
  margin: 0.6rem 0 0;
  font-size: 0.95rem;
  color: var(--ink-2);
  max-width: 62ch;
}
.entry__detail:last-child { margin-bottom: 0; }

/* ------------------------------------------------------ publications --- */

.pub-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
}
.chip {
  font: inherit;
  font-size: 0.85rem;
  padding: 0.42rem 0.85rem;
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius);
  background: transparent;
  color: var(--ink-2);
  cursor: pointer;
  transition: background 0.18s var(--ease), border-color 0.18s var(--ease),
              color 0.18s var(--ease);
}
.chip:hover { border-color: var(--accent); color: var(--accent); }
.chip[aria-pressed="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: #FCFEFD;
}
@media (prefers-color-scheme: dark) {
  .chip[aria-pressed="true"] { color: #0E1917; }
}

.pubs { display: grid; }

.pub {
  display: grid;
  grid-template-columns: 4.5rem 1fr;
  gap: 1.75rem;
  padding-block: 1.45rem;
  border-top: 1px solid var(--rule);
}
.pub:first-child { border-top: 0; padding-top: 0; }
.pub[hidden] { display: none; }
.pub > div:last-child { max-width: 68ch; }

.pub__year {
  font-size: 0.875rem;
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
  padding-top: 0.28rem;
}
.pub__title {
  font-family: var(--ff-display);
  font-size: 1.12rem;
  line-height: 1.35;
  font-weight: 500;
}
.pub__title a { color: var(--ink); text-decoration: none; }
.pub__title a:hover { color: var(--accent); text-decoration: underline; }
.pub__authors {
  margin: 0.4rem 0 0;
  font-size: 0.9rem;
  color: var(--ink-2);
}
.pub__authors b { color: var(--ink); font-weight: 500; }
.pub__venue {
  margin: 0.2rem 0 0;
  font-size: 0.9rem;
  color: var(--ink-2);
}
.pub__venue em { font-style: italic; color: var(--ink); }

.pub__status {
  display: inline-block;
  margin: 0.45rem 0 0 0.4rem;
  padding: 0.16rem 0.5rem;
  border: 1px dashed var(--rule-strong);
  border-radius: var(--radius);
  color: var(--ink-2);
  font-size: 0.8rem;
}

.pub__if {
  display: inline-block;
  margin: 0.45rem 0 0;
  padding: 0.16rem 0.5rem;
  border: 1px solid var(--accent-line);
  border-radius: var(--radius);
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.8rem;
  font-variant-numeric: tabular-nums;
}

.pub-empty {
  padding: 2.5rem 0;
  color: var(--ink-2);
  font-size: 0.95rem;
}

.pub-more {
  margin-top: 2.25rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem 1.5rem;
  font-size: 0.925rem;
  color: var(--ink-2);
}

/* ----------------------------------------------------- collaborators --- */

/* A hairline-divided roster: unlike a tile grid it always fills, whatever the
   number of collaborators. */
.people { border-top: 1px solid var(--rule); }

.people__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) minmax(0, 1.5fr);
  gap: 1.75rem;
  align-items: baseline;
  padding-block: 1.3rem;
  border-bottom: 1px solid var(--rule);
}

.people__name {
  font-family: var(--ff-display);
  font-size: 1.08rem;
  line-height: 1.3;
  font-weight: 500;
}
.people__name a { color: inherit; text-decoration: none; }
.people__name a:hover { color: var(--accent); }

.people__where,
.people__what {
  font-size: 0.925rem;
  color: var(--ink-2);
}

/* -------------------------------------------- teaching / recognition --- */

.two-col {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 3.5rem;
}
.col-title {
  font-family: var(--ff-display);
  font-size: 1.3rem;
  font-weight: 500;
  margin-bottom: 1.25rem;
}
.stack li {
  padding-block: 0.95rem;
  border-top: 1px solid var(--rule);
  font-size: 0.95rem;
  color: var(--ink-2);
  max-width: 58ch;
}
.stack li:first-child { border-top: 0; padding-top: 0; }
.stack strong { display: block; color: var(--ink); font-weight: 500; }
.stack .when { color: var(--ink-3); font-size: 0.85rem; }

/* ----------------------------------------------------------- contact --- */

.contact {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 3.5rem;
  align-items: start;
}
.contact__lede {
  font-size: 1.0625rem;
  color: var(--ink-2);
  max-width: 46ch;
}
.contact__list li {
  display: grid;
  grid-template-columns: 7.5rem 1fr;
  gap: 1rem;
  padding-block: 0.85rem;
  border-top: 1px solid var(--rule);
  font-size: 0.95rem;
}
.contact__list li:first-child { border-top: 0; padding-top: 0; }
.contact__key { color: var(--ink-3); }

.footer {
  border-top: 1px solid var(--rule);
  padding-block: 2rem 2.5rem;
  font-size: 0.85rem;
  color: var(--ink-3);
}
.footer__inner {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
  justify-content: space-between;
}

/* ----------------------------------------------------- page-load move --- */

@media (prefers-reduced-motion: no-preference) {
  .rise {
    opacity: 0;
    transform: translateY(14px);
    animation: rise 0.7s var(--ease) forwards;
  }
  .rise--1 { animation-delay: 0.05s; }
  .rise--2 { animation-delay: 0.14s; }
  .rise--3 { animation-delay: 0.23s; }
  .rise--4 { animation-delay: 0.32s; }
}
@keyframes rise {
  to { opacity: 1; transform: none; }
}

/* -------------------------------------------------------- responsive --- */

@media (max-width: 900px) {
  :root { --section-y: 4rem; }

  .hero__body {
    grid-template-columns: 1fr;
    gap: 1.5rem;
    padding-bottom: 3rem;
  }
  .hero__portrait { width: 152px; margin-top: -4.25rem; }
  .hero__text { padding-top: 0; }
  .hero__contact { flex-direction: row; flex-wrap: wrap; gap: 0.5rem 1.25rem; }

  .metrics__grid { grid-template-columns: repeat(2, 1fr); }
  .metrics__cell:nth-child(3) { border-left: 0; padding-left: 0; }
  .metrics__cell:nth-child(n + 3) { border-top: 1px solid var(--rule); }

  .themes { grid-template-columns: 1fr; }
  .theme, .theme--wide, .theme--lead { grid-column: span 1; }
  .theme--lead { grid-template-columns: 1fr; gap: 0.7rem; }

  .bio { grid-template-columns: 1fr; gap: 2.5rem; }
  .contact { grid-template-columns: 1fr; gap: 2.5rem; }
  .two-col { gap: 2.5rem; }

  .people__row {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr);
    gap: 0.35rem 1.25rem;
  }
  .people__what { grid-column: 1 / -1; }
}

@media (max-width: 680px) {
  :root { --gutter: 1.25rem; }

  .nav { height: auto; padding-block: 0.65rem; }
  .nav__inner { flex-wrap: wrap; gap: 0.5rem 1.1rem; }
  .nav__links {
    margin-left: 0;
    width: 100%;
    gap: 1.1rem;
    font-size: 0.85rem;
    overflow-x: auto;
    scrollbar-width: none;
    padding-bottom: 0.1rem;
  }
  .nav__links::-webkit-scrollbar { display: none; }
  html { scroll-padding-top: 7.5rem; }

  /* Narrow screens cannot crop past the NUS crest without slicing it, so show
     the banner whole instead. */
  .hero__band { height: auto; aspect-ratio: 990 / 247; }
  .hero__band img { object-position: center center; }

  .entry { grid-template-columns: 1fr; gap: 0.35rem; }
  .entry__when { padding-top: 0; order: -1; }

  .people__row { grid-template-columns: 1fr; gap: 0.2rem; }
  .people__what { grid-column: auto; }

  .pub { grid-template-columns: 1fr; gap: 0.3rem; }
  .pub__year { padding-top: 0; order: -1; }

  .contact__list li { grid-template-columns: 1fr; gap: 0.15rem; }
}

@media (max-width: 360px) {
  .metrics__grid { grid-template-columns: 1fr; }
  .metrics__cell { border-left: 0; padding-left: 0; }
  .metrics__cell + .metrics__cell { border-top: 1px solid var(--rule); }
}

@media print {
  .nav, .hero__band, .hero__actions, .pub-toolbar { display: none; }
  body { background: #fff; color: #000; }
}