/* Ruixing Zhang — world-model portfolio */

:root {
  --void: #0c1220;
  --depth: #141e32;
  --surface: #f3f0e8;
  --surface-raised: #ffffff;
  --ink: #1a2233;
  --ink-muted: #5a6478;
  --signal: #c4613a;
  --signal-soft: rgba(196, 97, 58, 0.12);
  --trajectory: #3d6fd4;
  --trajectory-soft: rgba(61, 111, 212, 0.14);
  --horizon: #e8c87a;
  --line: rgba(12, 18, 32, 0.1);
  --radius: 10px;
  --radius-lg: 16px;
  --shadow: 0 12px 40px rgba(12, 18, 32, 0.08);
  --font-display: "Syne", system-ui, sans-serif;
  --font-body: "Literata", Georgia, serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;
  --max: 920px;
  --nav-h: 3.5rem;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 1.5rem);
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1.05rem;
  line-height: 1.72;
  color: var(--ink);
  background: var(--surface);
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: var(--trajectory);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 0.2s;
}

a:hover { color: var(--signal); }

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--trajectory);
  outline-offset: 3px;
}

/* ── Nav ── */

.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(243, 240, 232, 0.88);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.site-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.15rem 1.25rem;
  list-style: none;
  margin: 0;
  padding: 0 1.25rem;
  justify-content: center;
}

.site-nav a {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--ink-muted);
}

.site-nav a:hover,
.site-nav a.is-active { color: var(--signal); }

/* ── Hero ── */

.hero {
  position: relative;
  overflow-x: hidden;
  background: var(--void);
  color: #e8ecf4;
  padding: 4.5rem 1.5rem 5rem;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(180deg, transparent 55%, rgba(232, 200, 122, 0.08) 100%),
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 39px,
      rgba(61, 111, 212, 0.07) 39px,
      rgba(61, 111, 212, 0.07) 40px
    ),
    repeating-linear-gradient(
      90deg,
      transparent,
      transparent 39px,
      rgba(61, 111, 212, 0.07) 39px,
      rgba(61, 111, 212, 0.07) 40px
    );
  pointer-events: none;
}

.hero-inner {
  position: relative;
  max-width: var(--max);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 2rem 2.5rem;
  align-items: start;
}

.hero-text {
  overflow: visible;
  padding-top: 0.35rem;
}

.avatar-wrap {
  border-radius: 50%;
  overflow: hidden;
  border: 2px solid rgba(232, 200, 122, 0.35);
  box-shadow: 0 0 0 6px rgba(61, 111, 212, 0.12);
}

.avatar-wrap img {
  width: 140px;
  height: 140px;
  object-fit: cover;
}

.hero-text .name-en {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: clamp(1.85rem, 4.5vw, 2.65rem);
  font-weight: 600;
  line-height: 1.35;
  margin: 0 0 0.2rem;
  letter-spacing: -0.01em;
}

.hero-text .name-cn {
  font-family: var(--font-display);
  font-size: clamp(1.7rem, 4vw, 2.45rem);
  font-weight: 600;
  color: var(--horizon);
  line-height: 1.2;
  margin: 0 0 0.65rem;
}

.hero-text .role {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: rgba(232, 236, 244, 0.65);
  margin: 0;
}

.hero-text .role span { color: var(--horizon); }

.hero-thesis {
  grid-column: 1 / -1;
  margin: 0.5rem 0 0;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  font-size: 0.98rem;
  color: rgba(232, 236, 244, 0.82);
  max-width: 52em;
}

.hero-thesis em {
  font-style: normal;
  color: var(--horizon);
}

/* ── Main layout ── */

main {
  max-width: var(--max);
  margin: 0 auto;
  padding: 3rem 1.5rem 5rem;
}

.section {
  margin-bottom: 4rem;
}

.section-header {
  margin-bottom: 1.75rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid var(--ink);
}

.section-header h2 {
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 700;
  margin: 0;
  letter-spacing: -0.02em;
}

.section-header .section-cn {
  font-weight: 600;
  color: var(--ink-muted);
}

/* ── Prose blocks ── */

.prose-block {
  margin-bottom: 1.25rem;
}

.prose-block p {
  margin: 0;
}

.prose-block + .prose-block {
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
}

.prose-block .lang-tag {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: 0.35rem;
}

.highlight {
  color: var(--signal);
  font-weight: 600;
}

/* ── Publications & projects ── */

.paper-list,
.project-list,
.talk-list {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.paper-card,
.project-card,
.talk-card {
  display: grid;
  grid-template-columns: 148px 1fr;
  gap: 1.25rem;
  padding: 1.25rem;
  background: var(--surface-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  transition: border-color 0.25s, transform 0.25s;
}

.paper-card:hover,
.project-card:hover,
.talk-card:hover {
  border-color: rgba(61, 111, 212, 0.25);
  transform: translateY(-2px);
}

.paper-thumb a,
.project-thumb a,
.talk-thumb a {
  display: block;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line);
}

.paper-thumb img,
.project-thumb img,
.talk-thumb img {
  width: 100%;
  aspect-ratio: 4/3;
  object-fit: cover;
}

.paper-body h3,
.project-body h3,
.talk-body h3 {
  font-family: var(--font-body);
  font-size: 1.02rem;
  font-weight: 600;
  line-height: 1.45;
  margin: 0 0 0.4rem;
  color: var(--ink);
}

.paper-authors {
  font-size: 0.92rem;
  color: var(--ink-muted);
  margin-bottom: 0.5rem;
}

.paper-authors .self {
  text-decoration: underline;
  text-decoration-color: var(--signal);
  text-underline-offset: 2px;
  color: var(--ink);
  font-weight: 600;
}

.venue {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.03em;
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
  margin-bottom: 0.55rem;
}

.venue--top {
  background: var(--signal-soft);
  color: var(--signal);
  font-weight: 600;
}

.venue--preprint {
  background: var(--trajectory-soft);
  color: var(--trajectory);
}

.paper-links,
.project-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
}

.paper-links a,
.project-links a {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-decoration: none;
  color: var(--ink-muted);
  border: 1px solid var(--line);
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  transition: border-color 0.2s, color 0.2s;
}

.paper-links a:hover,
.project-links a:hover {
  border-color: var(--trajectory);
  color: var(--trajectory);
}

.project-desc {
  font-size: 0.92rem;
  color: var(--ink-muted);
  margin: 0.35rem 0 0.5rem;
}

.project-tech {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-muted);
}

.talk-body h3 a {
  color: inherit;
  text-decoration: none;
}

.talk-body h3 a:hover {
  color: var(--trajectory);
}

.talk-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1rem;
  margin-top: 0.5rem;
}

.talk-views {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #c4613a;
}

.talk-links a {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-decoration: none;
  color: var(--ink-muted);
  border: 1px solid var(--line);
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  transition: border-color 0.2s, color 0.2s;
}

.talk-links a:hover {
  border-color: #00a1d6;
  color: #00a1d6;
}

/* ── Marathon timeline ── */

.run-intro {
  margin-bottom: 2rem;
}

.run-intro .prose-block p {
  font-size: 0.98rem;
}

.timeline {
  position: relative;
  padding-left: 1.5rem;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.5rem;
  bottom: 0.5rem;
  width: 2px;
  background: linear-gradient(180deg, var(--signal), var(--trajectory));
  border-radius: 1px;
}

.run-item {
  position: relative;
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 1rem;
  padding: 1rem 0 1rem 1.25rem;
  border-bottom: 1px solid var(--line);
}

.run-item:last-child { border-bottom: none; }

.run-item::before {
  content: "";
  position: absolute;
  left: -1.5rem;
  top: 1.35rem;
  width: 10px;
  height: 10px;
  margin-left: -4px;
  border-radius: 50%;
  background: var(--surface);
  border: 2px solid var(--signal);
}

.run-thumb a {
  display: block;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line);
}

.run-thumb img {
  width: 72px;
  height: 72px;
  object-fit: cover;
}

.run-body h3 {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 0.15rem;
}

.run-distance {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-muted);
  margin: 0;
}

.run-badge {
  display: inline-block;
  margin-top: 0.35rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--signal);
  background: var(--signal-soft);
  padding: 0.15rem 0.45rem;
  border-radius: 4px;
}

/* ── Lists (honors, service) ── */

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

.simple-list li {
  padding: 0.85rem 0;
  border-bottom: 1px solid var(--line);
  font-size: 0.96rem;
}

.simple-list li:first-child { padding-top: 0; }

.simple-list .year {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--signal);
  margin-right: 0.5rem;
}

/* ── Contact ── */

.contact-card {
  background: var(--void);
  color: #d8dde8;
  padding: 2rem 2.25rem;
  border-radius: var(--radius-lg);
  position: relative;
  overflow: hidden;
}

.contact-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(
    90deg,
    transparent,
    transparent 29px,
    rgba(61, 111, 212, 0.06) 29px,
    rgba(61, 111, 212, 0.06) 30px
  );
  pointer-events: none;
}

.contact-card > * { position: relative; }

.contact-card address {
  font-style: normal;
  line-height: 1.8;
  margin-bottom: 1.25rem;
}

.contact-card a {
  color: var(--horizon);
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

.contact-card a:hover { color: #fff; }

.contact-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
}

/* ── Footer ── */

.site-footer {
  text-align: center;
  padding: 2rem 1.5rem 3rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--ink-muted);
  letter-spacing: 0.04em;
}

/* ── Lightbox (minimal) ── */

.lightbox-target {
  position: fixed;
  inset: 0;
  background: rgba(12, 18, 32, 0.92);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s;
}

.lightbox-target:target {
  opacity: 1;
  pointer-events: auto;
}

.lightbox-target img {
  max-width: min(92vw, 900px);
  max-height: 88vh;
  border-radius: var(--radius);
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.5);
}

.lightbox-close {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  color: #fff;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  text-decoration: none;
  opacity: 0.7;
}

.lightbox-close:hover { opacity: 1; color: #fff; }

/* ── Responsive ── */

@media (max-width: 720px) {
  .hero-inner {
    grid-template-columns: 1fr;
    text-align: center;
    justify-items: center;
  }

  .hero-thesis { text-align: left; }

  .paper-card,
  .project-card,
  .talk-card {
    grid-template-columns: 1fr;
  }

  .paper-thumb,
  .talk-thumb { max-width: 200px; }

  .run-item {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }

  .run-thumb img {
    width: 100%;
    height: auto;
    max-height: 160px;
  }

  .site-nav ul {
    gap: 0.1rem 0.75rem;
  }

  .site-nav a { font-size: 0.65rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .paper-card:hover,
  .project-card:hover,
  .talk-card:hover { transform: none; }
}