/* =========================================================
   Suyu (Michael) Ye — personal site
   Modern minimal, single page. No framework.
   ========================================================= */

/* ----------  Design tokens  ---------- */
:root {
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-serif: "Newsreader", Georgia, "Times New Roman", serif;

  /* Light theme */
  --bg: #fbfbfa;
  --bg-soft: #f3f4f3;
  --surface: #ffffff;
  --surface-2: #f7f8f7;
  --text: #18201f;
  --text-soft: #44504e;
  --text-muted: #5b6664;
  --border: #e6e8e6;
  --border-strong: #d6dad8;
  --accent: #0f766e;
  --accent-strong: #0b5a54;
  --accent-soft: rgba(15, 118, 110, 0.10);
  --accent-contrast: #ffffff;
  --star: #c2410c;
  --shadow-sm: 0 1px 2px rgba(16, 24, 23, 0.05), 0 1px 3px rgba(16, 24, 23, 0.06);
  --shadow-md: 0 6px 16px rgba(16, 24, 23, 0.06), 0 2px 6px rgba(16, 24, 23, 0.05);
  --shadow-lg: 0 18px 50px rgba(16, 24, 23, 0.12);
  --nav-bg: rgba(251, 251, 250, 0.78);
  --radius: 14px;
  --radius-sm: 10px;
  --maxw: 920px;
  --nav-h: 64px;
}

[data-theme="dark"] {
  --bg: #0b1220;
  --bg-soft: #0e1626;
  --surface: #121b2c;
  --surface-2: #1c2840;
  --text: #e9eef5;
  --text-soft: #b6c2d3;
  --text-muted: #8492a6;
  --border: #1f2b40;
  --border-strong: #2a3852;
  --accent: #2dd4bf;
  --accent-strong: #5eead4;
  --accent-soft: rgba(45, 212, 191, 0.12);
  --accent-contrast: #06231f;
  --star: #fb923c;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 24px 60px rgba(0, 0, 0, 0.5);
  --nav-bg: rgba(11, 18, 32, 0.72);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 8px);
  -webkit-text-size-adjust: 100%;
}

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

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color 0.3s ease, color 0.3s ease;
}

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

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

.hero__bio a, .news__body a {
  text-decoration: underline;
  text-decoration-color: var(--accent-soft);
  text-underline-offset: 3px;
  text-decoration-thickness: 1.5px;
  transition: text-decoration-color 0.2s ease, color 0.2s ease;
}
.hero__bio a:hover, .news__body a:hover { text-decoration-color: var(--accent); }

h1, h2, h3 { line-height: 1.2; font-weight: 600; }

.icon {
  width: 1.15em;
  height: 1.15em;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex: none;
}
/* Solid glyph icons (brand logos) fill instead of stroke */
.icon--solid { fill: currentColor; stroke: none; }

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--accent);
  color: var(--accent-contrast);
  padding: 10px 16px;
  border-radius: 0 0 8px 0;
  z-index: 200;
}
.skip-link:focus { left: 0; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

.muted { color: var(--text-muted); }
.star { color: var(--star); font-weight: 700; }
.dot { color: var(--text-muted); margin: 0 0.4em; }

/* ----------  Layout helpers  ---------- */
.section {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 64px 24px;
}
.section + .section { padding-top: 24px; }

.eyebrow {
  font-family: var(--font-sans);
  text-transform: uppercase;
  letter-spacing: 0.16em;
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--accent);
  margin: 0 0 10px;
}

.section__head { margin-bottom: 36px; }
.section__title {
  font-family: var(--font-serif);
  font-size: clamp(1.7rem, 4vw, 2.3rem);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0;
}
.section__lead {
  margin: 14px 0 0;
  color: var(--text-soft);
  max-width: 60ch;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}

/* ----------  Buttons / chips  ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 0.92rem;
  border-radius: 999px;
  padding: 10px 18px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease, transform 0.18s ease;
}
.btn--sm { padding: 7px 13px; font-size: 0.86rem; }
.btn--primary { background: var(--accent); color: var(--accent-contrast); }
.btn--primary:hover { background: var(--accent-strong); color: var(--accent-contrast); transform: translateY(-1px); }
.btn--ghost {
  background: transparent;
  border-color: var(--border-strong);
  color: var(--text-soft);
}
.btn--ghost:hover { border-color: var(--accent); color: var(--accent); }
.btn--ok { background: var(--accent-strong) !important; color: var(--accent-contrast) !important; }

.icon-btn {
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: 1px solid transparent;
  background: transparent;
  color: var(--text-soft);
  cursor: pointer;
  font-size: 1.1rem;
  transition: background-color 0.18s ease, color 0.18s ease;
}
.icon-btn:hover { background: var(--bg-soft); color: var(--accent); }

/* ----------  Nav  ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease, background-color 0.3s ease;
}
.nav.is-scrolled { border-bottom-color: var(--border); }
.nav__inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  gap: 18px;
}
.nav__brand {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 1.2rem;
  color: var(--text);
  letter-spacing: -0.01em;
}
.nav__brand:hover { color: var(--accent); }
.nav__links {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}
.nav__link {
  position: relative;
  color: var(--text-soft);
  font-size: 0.93rem;
  font-weight: 500;
  padding: 8px 12px;
  border-radius: 8px;
  transition: color 0.18s ease, background-color 0.18s ease;
}
.nav__link:hover { color: var(--accent); background: var(--accent-soft); }
.nav__link.is-active { color: var(--accent); }
.nav__link.is-active::after {
  content: "";
  position: absolute;
  left: 12px; right: 12px; bottom: 2px;
  height: 2px;
  background: var(--accent);
  border-radius: 2px;
}
.nav__actions {
  display: flex;
  align-items: center;
  gap: 6px;
}
.cv-btn { margin-right: 2px; }

/* Theme toggle icon swap */
#themeToggle .icon--moon { display: none; }
[data-theme="dark"] #themeToggle .icon--sun { display: none; }
[data-theme="dark"] #themeToggle .icon--moon { display: block; }

/* Burger only on mobile */
.nav__burger { display: none; }
.nav__burger .icon--close { display: none; }

/* ----------  Hero  ---------- */
.hero { padding-top: 60px; }
.hero__grid {
  display: grid;
  grid-template-columns: 1.45fr 0.9fr;
  gap: 48px;
  align-items: start;
}
.hero__name {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(2.6rem, 6vw, 3.8rem);
  line-height: 1.04;
  letter-spacing: -0.02em;
  margin: 0 0 12px;
}
.hero__alt { color: var(--text-muted); font-style: italic; font-weight: 400; }
.hero__roles {
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--text-soft);
  margin: 0 0 22px;
}
.hero__bio {
  color: var(--text-soft);
  margin: 0 0 16px;
  max-width: 62ch;
}

.social {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 0;
  margin: 26px 0 0;
}
.social__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid var(--border-strong);
  background: var(--surface);
  color: var(--text-soft);
  font-size: 0.9rem;
  font-weight: 500;
  box-shadow: var(--shadow-sm);
  transition: color 0.18s ease, border-color 0.18s ease, transform 0.18s ease, background-color 0.18s ease;
}
.social__link:hover {
  color: var(--accent);
  border-color: var(--accent);
  transform: translateY(-2px);
}

/* Hero aside */
.hero__aside {
  display: flex;
  flex-direction: column;
  gap: 20px;
  position: sticky;
  top: 88px;
}
.portrait {
  position: relative;
  border-radius: 20px;
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-md);
  aspect-ratio: 1 / 1;
  background: var(--bg-soft);
}
.portrait::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 20px;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.04);
  pointer-events: none;
}
.portrait img { width: 100%; height: 100%; object-fit: cover; }


/* ----------  Publications  ---------- */
.pubs { list-style: none; margin: 0; padding: 0; display: grid; gap: 18px; }
.pub {
  display: grid;
  grid-template-columns: 184px 1fr;
  gap: 22px;
  padding: 20px;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.pub:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); border-color: var(--border-strong); }

.pub__thumb {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: contain;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-2);
}
.thumb--placeholder {
  display: grid;
  place-items: center;
  color: var(--accent);
  background:
    radial-gradient(120% 120% at 0% 0%, var(--accent-soft), transparent 60%),
    var(--surface-2);
}
.thumb--placeholder .icon { width: 38px; height: 38px; stroke-width: 1.4; opacity: 0.8; }

.pub__body { min-width: 0; }
.badges { display: flex; flex-wrap: wrap; gap: 7px; margin-bottom: 9px; }
.badge {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  padding: 3px 9px;
  border-radius: 999px;
  border: 1px solid var(--border-strong);
  color: var(--text-muted);
  background: var(--surface-2);
  white-space: nowrap;
}
.badge--venue { color: var(--accent); border-color: var(--accent-soft); background: var(--accent-soft); }
.badge--preprint { color: var(--text-soft); }
.badge--accent { color: var(--accent-contrast); background: var(--accent); border-color: var(--accent); }
.badge--soft { color: var(--text-muted); }

.pub__title {
  font-size: 1.12rem;
  font-weight: 600;
  margin: 0 0 7px;
  letter-spacing: -0.01em;
}
.pub__title a { color: var(--text); transition: color 0.18s ease; }
.pub__title a:hover { color: var(--accent); }
.pub__authors { margin: 0 0 4px; color: var(--text-soft); font-size: 0.94rem; }
.pub__authors strong { color: var(--text); }
.pub__venue { margin: 0 0 14px; color: var(--text-muted); font-size: 0.88rem; font-style: italic; }

.pub__links { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.84rem;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 8px;
  border: 1px solid var(--border-strong);
  background: var(--surface);
  color: var(--text-soft);
  cursor: pointer;
  font-family: inherit;
  transition: color 0.16s ease, border-color 0.16s ease, background-color 0.16s ease;
}
.chip:hover { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }
.chip .icon { width: 15px; height: 15px; }
.chip--cite { color: var(--accent); border-color: var(--accent-soft); }

/* ----------  News  ---------- */
.news { list-style: none; margin: 0; padding: 0; display: grid; gap: 2px; }
.news__item {
  display: grid;
  grid-template-columns: 110px 1fr;
  gap: 18px;
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  align-items: baseline;
  transition: background-color 0.18s ease;
}
.news__item:hover { background: var(--surface-2); }
.news__date {
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  font-size: 0.86rem;
  color: var(--accent);
  white-space: nowrap;
  padding-top: 1px;
}
.news__body { color: var(--text-soft); }
.news__body strong { color: var(--text); font-weight: 600; }

/* ----------  Timeline  ---------- */
.timeline { list-style: none; margin: 0; padding: 0 0 0 26px; position: relative; }
.timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 22px;
  bottom: 22px;
  width: 2px;
  background: var(--border);
}
.timeline__item {
  position: relative;
  display: grid;
  grid-template-columns: 42px 1fr auto;
  align-items: center;
  gap: 16px;
  padding: 13px 0;
}
.timeline__item::before {
  content: "";
  position: absolute;
  left: -25.5px;
  top: 50%;
  transform: translateY(-50%);
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--bg);
  border: 2.5px solid var(--accent);
  box-shadow: 0 0 0 3px var(--bg);
}
.timeline__logo {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 9px;
  padding: 6px;
  box-shadow: var(--shadow-sm);
}
.timeline__logo img { max-width: 100%; max-height: 100%; width: auto; height: auto; display: block; }
.timeline__text { min-width: 0; }
.timeline__head { margin: 0; font-size: 1rem; line-height: 1.45; }
.timeline__org { font-weight: 700; color: var(--text); }
.timeline__role { color: var(--text-muted); }
.timeline__note { margin: 2px 0 0; color: var(--text-muted); font-size: 0.85rem; }
.timeline__date { color: var(--text-muted); font-size: 0.88rem; white-space: nowrap; font-variant-numeric: tabular-nums; }

.awards { margin-top: 42px; }
.awards__title { font-family: var(--font-serif); font-size: 1.15rem; font-weight: 600; margin: 0 0 16px; }
.awards__list { list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; }
.awards__list li { display: grid; grid-template-columns: 92px 1fr; gap: 18px; align-items: baseline; }
.awards__year { color: var(--accent); font-weight: 600; font-size: 0.86rem; font-variant-numeric: tabular-nums; white-space: nowrap; }
.awards__list li > span:last-child { color: var(--text-soft); }
@media (max-width: 720px) { .awards__list li { grid-template-columns: 1fr; gap: 2px; } }

/* ----------  Beyond / facts  ---------- */
.facts {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}
.fact {
  display: flex;
  gap: 14px;
  padding: 18px 20px;
  align-items: flex-start;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.fact:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.fact__icon { font-size: 1.6rem; line-height: 1; flex: none; }
.fact p { margin: 0; color: var(--text-soft); font-size: 0.95rem; }
.fact strong { color: var(--text); }

/* ----------  Footer  ---------- */
.footer {
  border-top: 1px solid var(--border);
  margin-top: 48px;
  background: var(--bg-soft);
}
.footer__inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 40px 24px;
  text-align: center;
}
.footer__name { font-family: var(--font-serif); font-size: 1.15rem; font-weight: 600; margin: 0 0 14px; }
.footer__social { list-style: none; display: flex; justify-content: center; gap: 16px; padding: 0; margin: 0 0 16px; }
.footer__social a { color: var(--text-muted); font-size: 1.25rem; transition: color 0.18s ease, transform 0.18s ease; display: inline-flex; }
.footer__social a:hover { color: var(--accent); transform: translateY(-2px); }
.footer__social .icon { stroke-width: 1.8; }
.footer__meta { color: var(--text-muted); font-size: 0.84rem; margin: 0; }

/* ----------  Back to top  ---------- */
.to-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: var(--accent);
  color: var(--accent-contrast);
  border: none;
  box-shadow: var(--shadow-md);
  cursor: pointer;
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: opacity 0.25s ease, transform 0.25s ease, background-color 0.18s ease;
  z-index: 90;
}
.to-top.is-visible { opacity: 1; transform: translateY(0); pointer-events: auto; }
.to-top:hover { background: var(--accent-strong); }
.to-top .icon { width: 20px; height: 20px; }

/* ----------  Modal  ---------- */
.modal {
  position: fixed;
  inset: 0;
  z-index: 300;
  display: grid;
  place-items: center;
  padding: 24px;
}
.modal[hidden] { display: none; }
.modal__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(8, 12, 20, 0.55);
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
  animation: fade 0.2s ease;
}
.modal__panel {
  position: relative;
  width: min(640px, 100%);
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  animation: pop 0.22s cubic-bezier(0.2, 0.8, 0.3, 1);
  overflow: hidden;
}
.modal__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
}
.modal__title { margin: 0; font-size: 1.05rem; font-family: var(--font-serif); }
.modal__code {
  margin: 0;
  padding: 20px;
  overflow: auto;
  background: var(--surface-2);
  font-family: "SFMono-Regular", ui-monospace, "JetBrains Mono", Menlo, Consolas, monospace;
  font-size: 0.82rem;
  line-height: 1.55;
  color: var(--text-soft);
  white-space: pre;
  flex: 1;
}
.modal__actions { padding: 14px 20px; border-top: 1px solid var(--border); display: flex; justify-content: flex-end; }

@keyframes fade { from { opacity: 0; } to { opacity: 1; } }
@keyframes pop { from { opacity: 0; transform: translateY(10px) scale(0.98); } to { opacity: 1; transform: none; } }

/* ----------  Reveal on scroll  ---------- */
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.is-in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .modal__backdrop, .modal__panel { animation: none; }
  .modal__panel { transform: none; }
}

/* ----------  Responsive  ---------- */
@media (max-width: 860px) {
  .hero__grid { grid-template-columns: 1fr; gap: 32px; }
  .hero__aside {
    position: static;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: stretch;
  }
  .portrait { width: 160px; height: 160px; aspect-ratio: 1 / 1; flex: none; }
}

@media (max-width: 720px) {
  body { font-size: 16px; }
  .section { padding: 48px 20px; }

  .nav__links {
    position: fixed;
    inset: var(--nav-h) 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    padding: 12px 16px 18px;
    margin: 0;
    box-shadow: var(--shadow-md);
    transform: translateY(-120%);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: transform 0.3s ease, opacity 0.3s ease, visibility 0s linear 0.3s;
  }
  .nav__links.is-open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transition: transform 0.3s ease, opacity 0.3s ease, visibility 0s;
  }
  .nav__link { padding: 12px 14px; border-radius: 10px; font-size: 1rem; }
  .nav__link.is-active::after { display: none; }
  .nav__link.is-active { background: var(--accent-soft); }
  .nav__burger { display: inline-grid; }
  .nav__burger.is-open .icon--menu { display: none; }
  .nav__burger.is-open .icon--close { display: block; }
  .cv-btn span { display: none; }
  .cv-btn { padding: 7px 10px; min-height: 44px; }

  /* Touch targets: WCAG 2.5.5 / Apple HIG 44px minimum */
  .chip { min-height: 44px; }
  .social__link { min-height: 44px; }
  .icon-btn { width: 44px; height: 44px; }
  .footer__social { gap: 8px; }
  .footer__social a { padding: 11px; }

  .pub { grid-template-columns: 1fr; gap: 16px; }
  .pub__thumb { aspect-ratio: 16 / 10; max-height: 260px; }

  .news__item { grid-template-columns: 1fr; gap: 2px; padding: 12px 14px; }
  .news__date { font-size: 0.8rem; }

  .timeline { padding-left: 22px; }
  .timeline__item { grid-template-columns: 40px 1fr; align-items: start; gap: 14px; padding: 12px 0; }
  .timeline__logo { width: 40px; height: 40px; padding: 5px; }
  .timeline__date { grid-column: 2; margin-top: 4px; }
  .timeline__item::before { top: 32px; transform: none; }

  .facts { grid-template-columns: 1fr; }

  .hero__aside { flex-direction: column; }
  .portrait { width: 150px; height: 150px; }
}

@media (max-width: 400px) {
  .social { gap: 8px; }
  .social__link span { font-size: 0.85rem; }
}

/* ----------  Print  ---------- */
@media print {
  .nav, .to-top, .skip-link, .modal { display: none !important; }
  .reveal { opacity: 1 !important; transform: none !important; transition: none !important; }
  body { background: #fff; color: #000; }
  a { color: #000; text-decoration: underline; }
  .card, .pub { box-shadow: none; border-color: #ccc; }
  * { -webkit-print-color-adjust: economy; print-color-adjust: economy; }
}