/* =========================================================
   Bimsara Sandaruwan Kahandawala — Research Portfolio
   Design system: "Optical" — seeing beneath the surface.
   Display: Fraunces (optical serif) · Body: IBM Plex Sans
   Data/labels: IBM Plex Mono · Motif: OCT depth-scan lines
   ========================================================= */

:root {
  --ink:        #0A0F1A;
  --ink-soft:   #131B2C;
  --ink-2:      #1C2740;
  --paper:      #FAFBFD;
  --paper-2:    #F1F4F9;
  --slate:      #55617A;
  --slate-2:    #808AA0;
  --line:       #E2E8F2;
  --line-strong:#CBD4E3;
  --accent:     #0E7490;  /* optical teal */
  --accent-ink: #0A5566;
  --accent-2:   #08B4CE;  /* scan-line cyan */
  --accent-wash:#E5F4F6;
  --amber:      #A9741A;
  --amber-wash: #FBF3E2;
  --emerald:    #0F8A6A;
  --emerald-wash:#E4F5EE;

  --maxw: 1120px;
  --radius: 18px;
  --radius-lg: 26px;

  --shadow-sm: 0 1px 2px rgba(10,15,26,.04), 0 1px 3px rgba(10,15,26,.06);
  --shadow-md: 0 4px 20px -6px rgba(10,15,26,.12), 0 2px 6px rgba(10,15,26,.05);
  --shadow-lg: 0 24px 60px -20px rgba(10,15,26,.28);

  --f-display: 'Fraunces', Georgia, serif;
  --f-body: 'IBM Plex Sans', system-ui, sans-serif;
  --f-mono: 'IBM Plex Mono', ui-monospace, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--f-body);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
  font-size: 16.5px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }

/* ---------- Layout ---------- */
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 26px; }
.section { padding: 92px 0; }
.section--tight { padding: 64px 0; }
.section--ink { background: var(--ink); color: #EBEEF5; }
.section--paper2 { background: var(--paper-2); }

/* ---------- Typography ---------- */
.display {
  font-family: var(--f-display);
  font-optical-sizing: auto;
  font-weight: 560;
  letter-spacing: -0.02em;
  line-height: 1.04;
  margin: 0;
}
h1.display { font-size: clamp(2.7rem, 6vw, 4.6rem); }
h2.display { font-size: clamp(2rem, 3.6vw, 2.9rem); }
h3.display { font-size: clamp(1.35rem, 2.2vw, 1.7rem); font-weight: 540; }

.eyebrow {
  font-family: var(--f-mono);
  font-size: .72rem;
  letter-spacing: .26em;
  text-transform: uppercase;
  color: var(--accent-ink);
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: .7em;
}
.eyebrow::before {
  content: "";
  width: 26px; height: 1px;
  background: var(--accent);
  display: inline-block;
}
.section--ink .eyebrow { color: var(--accent-2); }
.section--ink .eyebrow::before { background: var(--accent-2); }

.lead { font-size: 1.16rem; color: var(--slate); line-height: 1.62; }
.section--ink .lead { color: #AEB8CC; }
.muted { color: var(--slate); }
.mono { font-family: var(--f-mono); }

/* Highlighted author name (the whole point for supervisors) */
.me {
  color: var(--accent-ink);
  font-weight: 600;
  background: linear-gradient(transparent 62%, var(--accent-wash) 62%);
  padding: 0 1px;
  white-space: nowrap;
}

/* ---------- OCT depth-scan motif ---------- */
.scanlines {
  background-image: repeating-linear-gradient(
    to bottom,
    rgba(255,255,255,0.00) 0px,
    rgba(255,255,255,0.00) 3px,
    rgba(8,180,206,0.05) 3px,
    rgba(8,180,206,0.05) 4px
  );
}
.scan-divider {
  height: 46px;
  background:
    linear-gradient(90deg, transparent, rgba(8,180,206,.5), transparent) center/100% 1px no-repeat,
    repeating-linear-gradient(90deg, var(--line) 0 2px, transparent 2px 9px) center/100% 8px no-repeat;
  opacity: .9;
}

/* ---------- Navigation ---------- */
.nav {
  position: sticky; top: 0; z-index: 60;
  background: rgba(250,251,253,0.82);
  backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line);
}
.nav__inner {
  max-width: var(--maxw); margin: 0 auto;
  padding: 15px 26px;
  display: flex; align-items: center; justify-content: space-between;
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand__mark {
  width: 34px; height: 34px; border-radius: 9px;
  background: var(--ink); color: var(--accent-2);
  display: grid; place-items: center;
  font-family: var(--f-mono); font-weight: 600; font-size: .95rem;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,.06);
}
.brand__name { font-family: var(--f-display); font-weight: 560; font-size: 1.12rem; letter-spacing: -.01em; }
.brand__sub { font-family: var(--f-mono); font-size: .62rem; letter-spacing: .2em; color: var(--slate-2); text-transform: uppercase; }
.nav__links { display: flex; align-items: center; gap: 30px; }
.nav__links a {
  font-family: var(--f-mono); font-size: .78rem; letter-spacing: .08em;
  text-transform: uppercase; color: var(--slate); font-weight: 500;
  padding: 4px 0; position: relative; transition: color .2s;
}
.nav__links a:hover { color: var(--ink); }
.nav__links a.active { color: var(--accent-ink); }
.nav__links a.active::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: -3px;
  height: 2px; background: var(--accent);
}
.nav__cta {
  font-family: var(--f-mono); font-size: .74rem; letter-spacing: .06em;
  text-transform: uppercase; font-weight: 500;
  background: var(--ink); color: #fff; padding: 9px 16px; border-radius: 10px;
  transition: transform .2s, background .2s;
}
.nav__cta:hover { transform: translateY(-1px); background: var(--accent-ink); }
.nav__burger { display: none; background: none; border: 0; cursor: pointer; padding: 6px; color: var(--ink); }
.nav__mobile { display: none; border-top: 1px solid var(--line); background: var(--paper); }
.nav__mobile a {
  display: block; padding: 15px 26px; font-family: var(--f-mono);
  font-size: .82rem; letter-spacing: .12em; text-transform: uppercase;
  color: var(--slate); border-bottom: 1px solid var(--line);
}
.nav__mobile a:last-child { border-bottom: 0; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 9px;
  font-family: var(--f-mono); font-size: .78rem; letter-spacing: .04em;
  font-weight: 500; padding: 12px 20px; border-radius: 12px;
  border: 1px solid transparent; cursor: pointer;
  transition: transform .2s, box-shadow .2s, background .2s, border-color .2s;
}
.btn:hover { transform: translateY(-2px); }
.btn--primary { background: var(--ink); color: #fff; box-shadow: var(--shadow-md); }
.btn--primary:hover { background: var(--accent-ink); }
.btn--ghost { background: #fff; color: var(--ink); border-color: var(--line-strong); box-shadow: var(--shadow-sm); }
.btn--ghost:hover { border-color: var(--accent); color: var(--accent-ink); }
.btn--on-ink { background: rgba(255,255,255,.08); color: #fff; border-color: rgba(255,255,255,.16); }
.btn--on-ink:hover { background: rgba(255,255,255,.14); }

/* ---------- Badges / chips ---------- */
.badge {
  font-family: var(--f-mono); font-size: .64rem; letter-spacing: .12em;
  text-transform: uppercase; font-weight: 600;
  padding: 4px 9px; border-radius: 6px; display: inline-flex; align-items: center; gap: 5px;
}
.badge--q1 { background: var(--emerald-wash); color: var(--emerald); border: 1px solid #BBE6D6; }
.badge--q2 { background: var(--accent-wash); color: var(--accent-ink); border: 1px solid #BDE4E9; }
.badge--first { background: var(--ink); color: var(--accent-2); }
.badge--oa { background: var(--amber-wash); color: var(--amber); border: 1px solid #EBD9AE; }
.chip {
  font-family: var(--f-mono); font-size: .68rem; letter-spacing: .04em;
  color: var(--accent-ink); background: var(--accent-wash);
  border: 1px solid #C9E7EB; padding: 4px 10px; border-radius: 999px; display: inline-block;
}
.chip--plain { color: var(--slate); background: var(--paper-2); border-color: var(--line); }

/* ---------- Cards ---------- */
.card {
  background: #fff; border: 1px solid var(--line);
  border-radius: var(--radius-lg); box-shadow: var(--shadow-sm);
  transition: transform .35s cubic-bezier(.2,.7,.2,1), box-shadow .35s, border-color .35s;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--line-strong); }

/* ---------- Publication card ---------- */
.pub {
  position: relative; background: #fff; border: 1px solid var(--line);
  border-radius: var(--radius-lg); padding: 30px 32px 26px;
  box-shadow: var(--shadow-sm); overflow: hidden;
  transition: transform .35s cubic-bezier(.2,.7,.2,1), box-shadow .35s, border-color .35s;
}
.pub::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 4px;
  background: linear-gradient(var(--accent), var(--accent-2));
}
.pub:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--line-strong); }
.pub__index {
  font-family: var(--f-mono); font-size: .72rem; color: var(--slate-2);
  letter-spacing: .1em;
}
.pub__top { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-bottom: 14px; }
.pub__journal { font-family: var(--f-mono); font-size: .74rem; color: var(--slate); letter-spacing: .02em; }
.pub__title {
  font-family: var(--f-display); font-optical-sizing: auto;
  font-size: clamp(1.15rem, 1.9vw, 1.42rem); font-weight: 540; line-height: 1.22;
  letter-spacing: -.01em; margin: 0 0 12px; color: var(--ink);
}
.pub__authors { font-size: .92rem; color: var(--slate); line-height: 1.7; margin: 0 0 16px; }
.pub__meta { display: flex; flex-wrap: wrap; align-items: center; gap: 14px 20px; padding-top: 16px; border-top: 1px solid var(--line); }
.pub__doi { font-family: var(--f-mono); font-size: .74rem; color: var(--accent-ink); display: inline-flex; align-items: center; gap: 7px; transition: gap .2s; }
.pub__doi:hover { gap: 11px; }
.pub__tags { display: flex; flex-wrap: wrap; gap: 6px; margin-left: auto; }

/* ---------- Stat strip ---------- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; background: #fff; }
.stat { padding: 24px 22px; border-right: 1px solid var(--line); }
.stat:last-child { border-right: 0; }
.stat__num { font-family: var(--f-display); font-size: 2.4rem; font-weight: 560; line-height: 1; color: var(--ink); letter-spacing: -.02em; }
.stat__num sup { font-size: .9rem; color: var(--accent); font-family: var(--f-mono); top: -1.1em; }
.stat__label { font-family: var(--f-mono); font-size: .68rem; letter-spacing: .1em; text-transform: uppercase; color: var(--slate); margin-top: 8px; }

/* ---------- Timeline ---------- */
.tl { position: relative; padding-left: 30px; }
.tl::before { content: ""; position: absolute; left: 6px; top: 6px; bottom: 6px; width: 2px; background: var(--line); }
.tl__item { position: relative; margin-bottom: 34px; }
.tl__item:last-child { margin-bottom: 0; }
.tl__dot { position: absolute; left: -30px; top: 6px; width: 13px; height: 13px; border-radius: 50%; background: #fff; border: 3px solid var(--accent); box-shadow: 0 0 0 4px var(--accent-wash); }
.tl__dot--soft { border-color: var(--line-strong); box-shadow: 0 0 0 4px var(--paper-2); }

/* ---------- Skill groups ---------- */
.skillgrid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.skillgroup { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 22px 24px; box-shadow: var(--shadow-sm); }
.skillgroup h4 { font-family: var(--f-mono); font-size: .72rem; letter-spacing: .12em; text-transform: uppercase; color: var(--accent-ink); margin: 0 0 14px; display: flex; align-items: center; gap: 9px; }
.skillgroup__list { display: flex; flex-wrap: wrap; gap: 7px; }

/* ---------- Gallery / moments ---------- */
.gallery { display: grid; gap: 18px; }
.figure { position: relative; overflow: hidden; border-radius: var(--radius); border: 1px solid var(--line); background: #fff; cursor: zoom-in; box-shadow: var(--shadow-sm); }
.figure img { width: 100%; height: 100%; object-fit: cover; transition: transform .6s cubic-bezier(.2,.7,.2,1); }
.figure:hover img { transform: scale(1.04); }
.figure__cap { position: absolute; inset: auto 0 0 0; padding: 16px 16px 13px; background: linear-gradient(transparent, rgba(10,15,26,.85)); color: #fff; }
.figure__cap b { font-family: var(--f-display); font-weight: 500; font-size: 1rem; }
.figure__cap span { display: block; font-family: var(--f-mono); font-size: .64rem; letter-spacing: .1em; text-transform: uppercase; color: #9FD9E3; margin-top: 3px; }

/* ---------- Lightbox ---------- */
.lb { position: fixed; inset: 0; z-index: 120; display: none; background: rgba(6,9,16,.94); backdrop-filter: blur(6px); padding: 40px 24px; overflow: auto; }
.lb.open { display: grid; place-items: center; }
.lb__img { max-width: min(1000px, 94vw); max-height: 82vh; border-radius: 12px; box-shadow: var(--shadow-lg); }
.lb__cap { color: #C7D0E0; font-family: var(--f-mono); font-size: .8rem; text-align: center; margin-top: 18px; letter-spacing: .04em; }
.lb__close { position: fixed; top: 22px; right: 26px; background: none; border: 0; color: #fff; font-size: 2.4rem; line-height: 1; cursor: pointer; opacity: .8; }
.lb__close:hover { opacity: 1; }

/* ---------- Footer ---------- */
.footer { background: var(--ink); color: #97A2B8; padding: 66px 0 40px; }
.footer__grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 40px; margin-bottom: 46px; }
.footer h5 { font-family: var(--f-mono); font-size: .68rem; letter-spacing: .16em; text-transform: uppercase; color: var(--slate-2); margin: 0 0 16px; }
.footer a { color: #C4CCDC; transition: color .2s; }
.footer a:hover { color: var(--accent-2); }
.footer__links { display: flex; flex-direction: column; gap: 10px; font-size: .94rem; }
.footer__brand-name { font-family: var(--f-display); color: #fff; font-size: 1.4rem; font-weight: 540; margin: 0 0 10px; }
.footer__social { display: flex; gap: 14px; margin-top: 18px; }
.footer__social a { width: 40px; height: 40px; border-radius: 10px; background: rgba(255,255,255,.06); display: grid; place-items: center; color: #C4CCDC; font-size: 1.05rem; transition: background .2s, color .2s, transform .2s; }
.footer__social a:hover { background: var(--accent-ink); color: #fff; transform: translateY(-2px); }
.footer__bottom { border-top: 1px solid rgba(255,255,255,.08); padding-top: 26px; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; font-family: var(--f-mono); font-size: .72rem; letter-spacing: .06em; color: var(--slate-2); }

/* ---------- Reveal animation ---------- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .7s ease, transform .7s cubic-bezier(.2,.7,.2,1); }
.reveal.in { opacity: 1; transform: none; }

/* ---------- Utilities ---------- */
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 26px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.stack-lg > * + * { margin-top: 22px; }
.center { text-align: center; }
.mt-s { margin-top: 10px; } .mt-m { margin-top: 20px; } .mt-l { margin-top: 34px; }
.divider-line { height: 1px; background: var(--line); border: 0; margin: 0; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .nav__links { display: none; }
  .nav__burger { display: block; }
  .nav__cta { display: none; }
  .nav__mobile.open { display: block; }
  /* Collapse every multi-column grid (class-based AND inline) to one column */
  .grid-2, .grid-3, .skillgrid { grid-template-columns: 1fr; }
  [style*="grid-template-columns"] { grid-template-columns: 1fr !important; }
  [style*="gap:56px"], [style*="gap:48px"] { gap: 34px !important; }
  .stats { grid-template-columns: 1fr 1fr; }
  .stat:nth-child(2) { border-right: 0; }
  .stat:nth-child(1), .stat:nth-child(2) { border-bottom: 1px solid var(--line); }
  .footer__grid { grid-template-columns: 1fr; gap: 30px; }
  .section { padding: 60px 0; }
  .section--tight { padding: 48px 0; }
  .pub { padding: 24px 20px 20px; }
  .pub__tags { margin-left: 0; width: 100%; }
  /* Hero: image sits below text at a sensible size */
  header .wrap { gap: 30px !important; }
  header .wrap > div[style*="position:relative"] { max-width: 430px; width: 100%; margin: 6px auto 0; }
}
@media (max-width: 640px) {
  .wrap { padding: 0 20px; }
  .nav__inner { padding: 13px 20px; }
  h1.display { font-size: clamp(2.3rem, 9vw, 3rem); }
  .pub__title { font-size: 1.12rem; }
  .pub__top { gap: 6px; }
  .card[style*="grid-template-columns"] { text-align: left; }
  /* Award cards: icon above text instead of cramped side-by-side */
  .stack-lg .card[style*="grid-template-columns:auto"] { gap: 16px !important; }
}
@media (max-width: 520px) {
  .stats { grid-template-columns: 1fr; }
  .stat { border-right: 0; border-bottom: 1px solid var(--line); }
  .stat:last-child { border-bottom: 0; }
  body { font-size: 16px; }
  .btn { padding: 11px 16px; font-size: .74rem; }
}
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
  .reveal { opacity: 1; transform: none; }
}

/* ---------- Contact modal ---------- */
.modal { position: fixed; inset: 0; z-index: 130; display: none; place-items: center; background: rgba(6,9,16,.7); backdrop-filter: blur(5px); padding: 24px; }
.modal.open { display: grid; }
.modal__card { background: #fff; border-radius: var(--radius-lg); padding: 34px 34px 30px; max-width: 400px; width: 100%; box-shadow: var(--shadow-lg); position: relative; }
.modal__close { position: absolute; top: 16px; right: 18px; background: none; border: 0; font-size: 1.7rem; line-height: 1; color: var(--slate-2); cursor: pointer; }
.modal__close:hover { color: var(--ink); }
.modal h3 { font-family: var(--f-display); font-weight: 540; font-size: 1.5rem; margin: 0 0 20px; }
.modal__row { display: flex; align-items: center; gap: 14px; padding: 13px 0; border-top: 1px solid var(--line); }
.modal__row i { width: 40px; height: 40px; border-radius: 10px; background: var(--accent-wash); color: var(--accent-ink); display: grid; place-items: center; }
.modal__row span { font-family: var(--f-mono); font-size: .7rem; letter-spacing: .1em; text-transform: uppercase; color: var(--slate-2); display: block; }
.modal__row b { font-size: 1rem; color: var(--ink); font-weight: 500; }

/* ---------- Video tutorials ---------- */
.videos { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.video { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow-sm); transition: transform .35s cubic-bezier(.2,.7,.2,1), box-shadow .35s, border-color .35s; }
.video:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--line-strong); }
.video__frame { position: relative; aspect-ratio: 16/9; width: 100%; border: 0; padding: 0; margin: 0; cursor: pointer; background-color: var(--ink); background-size: cover; background-position: center; display: block; overflow: hidden; }
.video__frame::after { content: ""; position: absolute; inset: 0; background: linear-gradient(180deg, rgba(10,15,26,.06), rgba(10,15,26,.34)); transition: background .3s; z-index: 1; }
.video__frame:hover::after { background: linear-gradient(180deg, rgba(10,15,26,.04), rgba(10,15,26,.14)); }
.video__play { position: absolute; top: 50%; left: 50%; transform: translate(-50%,-50%); z-index: 2; width: 58px; height: 58px; border-radius: 50%; background: rgba(14,116,144,.94); color: #fff; display: grid; place-items: center; font-size: 1.15rem; box-shadow: 0 8px 24px rgba(0,0,0,.32); transition: transform .3s, background .3s; }
.video__frame:hover .video__play { transform: translate(-50%,-50%) scale(1.08); background: var(--accent-2); }
.video__frame iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; z-index: 3; }
.video__body { padding: 16px 18px 18px; }
.video__tag { font-family: var(--f-mono); font-size: .62rem; letter-spacing: .12em; text-transform: uppercase; color: var(--accent-ink); }
.video__title { font-family: var(--f-display); font-size: 1.04rem; font-weight: 540; line-height: 1.26; margin: 6px 0 0; color: var(--ink); }
@media (max-width: 900px) { .videos { grid-template-columns: 1fr; } }