/* ============================================================
   Saumya Sadhu — personal site
   Design direction: "Contour lines" — the isoline motif reads
   as both lithographic etching (semiconductor) and atmospheric
   concentration maps (regionalised LCIA). One idea, both tracks.
   ============================================================ */

:root {
  /* Palette — cool technical paper, not warm cream */
  --paper:        #F3F5F6;
  --paper-2:      #FFFFFF;
  --ink:          #15181D;
  --ink-muted:    #545C66;
  --ink-faint:    #8B939C;
  --hairline:     #E0E4E8;
  --hairline-2:   #EAEDF0;

  /* Two research tracks */
  --thematic:     #4B41A6;  /* violet — the industry problem */
  --thematic-soft:#ECEAF7;
  --method:       #1F7D6C;  /* teal — the method */
  --method-soft:  #E4F0ED;
  --bridge:       #B96E23;  /* amber — where they meet */
  --bridge-soft:  #F6ECDF;

  --maxw: 1080px;
  --gutter: clamp(1.25rem, 5vw, 4rem);

  --font-display: "Space Grotesk", system-ui, sans-serif;
  --font-body:    "IBM Plex Sans", system-ui, sans-serif;
  --font-mono:    "IBM Plex Mono", ui-monospace, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

a { color: inherit; }

/* --- Shared type devices ---------------------------------- */

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 1.1rem;
  display: flex;
  align-items: center;
  gap: 0.7rem;
}
.eyebrow::before {
  content: "";
  width: 1.6rem;
  height: 1px;
  background: var(--ink-faint);
  display: inline-block;
}

h1, h2, h3 { font-family: var(--font-display); font-weight: 600; line-height: 1.1; }

section { padding-block: clamp(3.5rem, 9vw, 6.5rem); }
section + section { border-top: 1px solid var(--hairline); }

.section-head { max-width: 40rem; margin-bottom: clamp(2rem, 5vw, 3rem); }
.section-head h2 {
  font-size: clamp(1.7rem, 4vw, 2.4rem);
  margin: 0 0 0.9rem;
  letter-spacing: -0.01em;
}
.section-head p { margin: 0; color: var(--ink-muted); font-size: 1.075rem; }

/* --- Hero -------------------------------------------------- */

.hero {
  position: relative;
  overflow: hidden;
  border-top: none;
  padding-block: clamp(5rem, 14vw, 9rem);
}
.hero__contours {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  /* fallback wash if JS is disabled */
  background:
    radial-gradient(120% 90% at 82% 15%, rgba(75,65,166,0.06), transparent 55%),
    radial-gradient(90% 80% at 90% 60%, rgba(31,125,108,0.05), transparent 55%);
}
.hero__contours svg { width: 100%; height: 100%; display: block; }
.hero .wrap { position: relative; z-index: 1; }

.hero__grid { display: grid; gap: clamp(2rem, 5vw, 3.5rem); align-items: center; }
@media (min-width: 820px) {
  .hero__grid { grid-template-columns: 1.3fr 0.85fr; }
}
.hero__photo { margin: 0; }
.hero__photo img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 6px;
  box-shadow: 0 24px 55px -24px rgba(21, 24, 29, 0.4);
}
@media (min-width: 820px) {
  .hero__photo { max-width: 360px; margin-left: auto; }
}

.hero__role {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin: 0 0 1.4rem;
}
.hero h1 {
  font-size: clamp(2.9rem, 8vw, 5.2rem);
  letter-spacing: -0.03em;
  margin: 0 0 1.5rem;
  max-width: 14ch;
}
.hero__lead {
  font-size: clamp(1.15rem, 2.4vw, 1.4rem);
  line-height: 1.5;
  color: var(--ink-muted);
  max-width: 40ch;
  margin: 0 0 2.2rem;
}
.hero__lead strong { color: var(--ink); font-weight: 500; }

.hero__cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  letter-spacing: 0.03em;
  text-decoration: none;
  padding: 0.7rem 1.15rem;
  border: 1px solid var(--ink);
  border-radius: 2px;
  transition: background .18s ease, color .18s ease, transform .18s ease;
}
.hero__cta:hover { background: var(--ink); color: var(--paper); }
.hero__cta:focus-visible { outline: 2px solid var(--thematic); outline-offset: 3px; }
.hero__cta .arrow { transition: transform .18s ease; }
.hero__cta:hover .arrow { transform: translateX(3px); }

/* --- Research: two tracks + bridge (the signature) --------- */

.tracks {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  position: relative;
}
@media (min-width: 860px) {
  .tracks {
    grid-template-columns: 1fr 1fr;
    gap: 1.25rem;
  }
}

.track {
  background: var(--paper-2);
  border: 1px solid var(--hairline);
  border-radius: 4px;
  padding: 1.8rem 1.7rem;
  position: relative;
}
.track__tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  display: inline-block;
  padding: 0.28rem 0.6rem;
  border-radius: 2px;
  margin-bottom: 1rem;
}
.track--thematic { border-top: 3px solid var(--thematic); }
.track--thematic .track__tag { color: var(--thematic); background: var(--thematic-soft); }
.track--method  { border-top: 3px solid var(--method); }
.track--method .track__tag { color: var(--method); background: var(--method-soft); }

.track h3 { font-size: 1.3rem; margin: 0; letter-spacing: -0.01em; }

/* Bridge band spanning both columns */
.bridge {
  grid-column: 1 / -1;
  margin-top: 0.25rem;
  border: 1px dashed var(--bridge);
  background: var(--bridge-soft);
  border-radius: 4px;
  padding: 1.6rem 1.7rem;
}
.bridge__tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--bridge);
  margin: 0 0 1.1rem;
}
.bridge__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.8rem;
}
@media (min-width: 720px) {
  .bridge__list { grid-template-columns: 1fr 1fr; gap: 1.4rem; }
}
.bridge__list li {
  position: relative;
  padding-left: 1.4rem;
  font-size: 1.02rem;
  color: var(--ink);
}
.bridge__list li::before {
  content: "";
  position: absolute;
  left: 0; top: 0.62em;
  width: 0.55rem; height: 0.55rem;
  border: 1.5px solid var(--bridge);
  border-radius: 50%;
}

/* --- Selected work ---------------------------------------- */

.project {
  background: var(--paper-2);
  border: 1px solid var(--hairline);
  border-radius: 4px;
  padding: clamp(1.8rem, 4vw, 2.6rem);
  display: grid;
  gap: 1.4rem;
}
@media (min-width: 760px) {
  .project { grid-template-columns: minmax(0,1fr) minmax(0,1.6fr); align-items: start; }
}
.project__meta { display: flex; flex-direction: column; gap: 0.7rem; }
.project__status {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--method);
}
.project__name {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 4vw, 2.1rem);
  font-weight: 600;
  margin: 0;
  letter-spacing: -0.02em;
}
.project__body { margin: 0; color: var(--ink-muted); font-size: 1.06rem; }
.project__link {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  text-decoration: none;
  color: var(--method);
  border-bottom: 1px solid transparent;
  width: fit-content;
  transition: border-color .18s ease;
}
.project__link:hover { border-color: var(--method); }

/* --- Conferences ------------------------------------------ */

.confs { list-style: none; margin: 0; padding: 0; }
.confs li {
  padding: 1.4rem 0;
  border-top: 1px solid var(--hairline);
}
.confs li:last-child { border-bottom: 1px solid var(--hairline); }
.conf__top {
  display: flex;
  align-items: baseline;
  gap: 0.9rem;
  flex-wrap: wrap;
  margin-bottom: 0.5rem;
}
.conf__year { font-family: var(--font-mono); font-size: 0.95rem; color: var(--ink); }
.conf__venue { font-family: var(--font-display); font-weight: 500; font-size: 1.1rem; }
.conf__venue span { color: var(--ink-faint); font-size: 0.9rem; font-family: var(--font-body); }
.conf__note {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--thematic);
  border: 1px solid var(--thematic);
  border-radius: 2px;
  padding: 0.2rem 0.5rem;
  white-space: nowrap;
  margin-left: auto;
}
.conf__title { margin: 0; color: var(--ink-muted); font-size: 1.02rem; max-width: 64ch; }
@media (max-width: 560px) {
  .conf__note { margin-left: 0; }
}

/* --- Teaching --------------------------------------------- */

.teach__label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 0.9rem;
}
.teach__label + .teach__list { margin-bottom: 2.2rem; }
.teach__list { list-style: none; margin: 0; padding: 0; }
.teach__list li {
  position: relative;
  padding: 0.85rem 0 0.85rem 1.5rem;
  border-top: 1px solid var(--hairline-2);
  font-size: 1.05rem;
  max-width: 66ch;
}
.teach__list li::before {
  content: "";
  position: absolute;
  left: 0; top: 1.35em;
  width: 0.5rem; height: 1px;
  background: var(--method);
}
.teach__list li a { text-decoration: none; border-bottom: 1px solid var(--hairline); transition: border-color .18s ease; }
.teach__list li a:hover { border-color: var(--ink); }
.teach__list li a:focus-visible { outline: 2px solid var(--thematic); outline-offset: 3px; }

/* --- Publications (empty-but-alive state) ----------------- */

.pubs-note {
  border: 1px solid var(--hairline);
  border-left: 3px solid var(--method);
  background: var(--paper-2);
  border-radius: 4px;
  padding: 1.6rem 1.7rem;
  color: var(--ink-muted);
  max-width: 46rem;
}
.pubs-note strong { color: var(--ink); font-weight: 500; }

/* --- Contact ---------------------------------------------- */

.contact-grid { display: grid; gap: 2.5rem; }
@media (min-width: 720px) { .contact-grid { grid-template-columns: 1.2fr 1fr; } }

.contact__email {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 4vw, 2rem);
  font-weight: 500;
  text-decoration: none;
  letter-spacing: -0.01em;
  border-bottom: 2px solid var(--hairline);
  transition: border-color .18s ease;
  word-break: break-word;
}
.contact__email:hover { border-color: var(--thematic); }

.links { list-style: none; margin: 1.6rem 0 0; padding: 0; display: grid; gap: 0.9rem; }
.links a {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  text-decoration: none;
  display: inline-flex;
  gap: 0.6rem;
  align-items: center;
  width: fit-content;
  border-bottom: 1px solid transparent;
  transition: border-color .18s ease;
}
.links a::before { content: "→"; color: var(--ink-faint); }
.links a:hover { border-color: var(--ink); }
.links a:focus-visible { outline: 2px solid var(--thematic); outline-offset: 3px; }

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

.foot {
  border-top: 1px solid var(--hairline);
  padding-block: 2.5rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-faint);
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
  justify-content: space-between;
}

/* --- Scroll reveal (progressive, JS-driven, safe fallback) - */
.reveal { opacity: 0; transform: translateY(14px); }
.reveal.is-in { opacity: 1; transform: none; transition: opacity .6s ease, transform .6s ease; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; }
  .reveal.is-in { transition: none; }
}