/* HK XINGYI — minimal biotech research aesthetic */

:root {
  --bg: #f6f8f7;
  --bg-elevated: #ffffff;
  --ink: #14221e;
  --ink-muted: #5a6b65;
  --ink-soft: #8a9692;
  --accent: #1d5c4d;
  --accent-soft: #2a7a66;
  --line: #dfe8e4;
  --line-strong: #c5d4cd;
  --hero-overlay: rgba(20, 34, 30, 0.35);
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.75rem;
  --space-lg: 3rem;
  --space-xl: 5rem;
  --space-2xl: 7rem;
  --font-en: "Outfit", system-ui, sans-serif;
  --font-zh: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --max-content: 72rem;
  --narrow: 42rem;
  --header-h: 4rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 1rem;
  line-height: 1.65;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

/* Chinese copy uses Noto Sans SC */
.prose,
.hero-sub.zh,
.hero-tagline,
.section-title-zh,
.research-list .text,
.tech-card h3,
.tech-card p,
.academic-list li,
.cooperation-prose,
.footer-copy {
  font-family: var(--font-zh);
  font-weight: 300;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent-soft);
}

.container {
  width: min(100% - 2.5rem, var(--max-content));
  margin-inline: auto;
}

.container.narrow {
  width: min(100% - 2.5rem, var(--narrow));
}

/* Header */
.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  height: var(--header-h);
  background: rgba(246, 248, 247, 0.82);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  width: min(100% - 2rem, var(--max-content));
  height: 100%;
  margin-inline: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
}

.header-end {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  flex-shrink: 0;
}

.nav {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  min-width: 0;
}

.lang-switch {
  position: relative;
  z-index: 2;
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.5rem;
  height: 2.125rem;
  padding: 0 0.6rem;
  font-family: var(--font-en);
  font-weight: 500;
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  border: 1px solid var(--accent);
  border-radius: 2px;
  background: var(--bg-elevated);
  color: var(--accent);
  cursor: pointer;
  box-shadow: 0 1px 2px rgba(20, 34, 30, 0.06);
  transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

.lang-switch-inner {
  display: inline-block;
  line-height: 1;
}

.lang-switch:hover {
  color: var(--bg-elevated);
  background: var(--accent);
  border-color: var(--accent);
}

.logo {
  flex-shrink: 0;
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 1.05rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--ink);
}

.logo-sub {
  display: block;
  font-size: 0.65rem;
  letter-spacing: 0.35em;
  color: var(--accent);
  margin-top: 0.15rem;
}

.nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 2rem;
}

.nav-list a {
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 0.8125rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

.nav-list a:hover {
  color: var(--accent);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
}

.nav-toggle-bar {
  display: block;
  width: 100%;
  height: 1px;
  background: var(--ink);
}

@media (max-width: 768px) {
  .header-end {
    gap: 0.625rem;
  }

  .lang-switch {
    min-width: 2.375rem;
    height: 2rem;
    padding: 0 0.5rem;
    font-size: 0.75rem;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-list {
    position: fixed;
    inset: var(--header-h) 0 auto 0;
    flex-direction: column;
    gap: 0;
    padding: var(--space-md) 1.5rem var(--space-lg);
    background: var(--bg-elevated);
    border-bottom: 1px solid var(--line);
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.35s ease, opacity 0.35s ease;
  }

  .nav-list.is-open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-list li {
    border-bottom: 1px solid var(--line);
  }

  .nav-list a {
    display: block;
    padding: 1rem 0;
  }
}

/* Hero */
.hero {
  position: relative;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: calc(var(--header-h) + var(--space-lg)) var(--space-sm) var(--space-xl);
  text-align: center;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(165deg, rgba(246, 248, 247, 0.92) 0%, rgba(246, 248, 247, 0.75) 45%, rgba(220, 232, 226, 0.5) 100%),
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(45, 106, 92, 0.12), transparent),
    var(--bg);
  z-index: 0;
}

.hero-bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 4rem 4rem;
  opacity: 0.35;
  mask-image: linear-gradient(to bottom, black 20%, transparent 85%);
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 52rem;
}

.hero-label {
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 0.6875rem;
  letter-spacing: 0.35em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 var(--space-md);
}

.hero-title {
  margin: 0 0 var(--space-md);
  font-family: var(--font-en);
  font-weight: 200;
  font-size: clamp(1.35rem, 4vw, 2.35rem);
  line-height: 1.2;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.hero-sub {
  margin: 0;
  font-size: clamp(0.9rem, 2vw, 1.05rem);
  letter-spacing: 0.06em;
  color: var(--ink-muted);
}

.hero-sub.en {
  font-family: var(--font-en);
  font-weight: 300;
  margin-bottom: var(--space-sm);
}

.hero-sub.zh {
  font-size: clamp(0.875rem, 1.8vw, 0.98rem);
  color: var(--ink-soft);
  letter-spacing: 0.08em;
  margin-bottom: var(--space-lg);
}

.hero-tagline {
  margin: 0 0 var(--space-lg);
  font-size: clamp(0.85rem, 1.6vw, 0.95rem);
  letter-spacing: 0.12em;
  color: var(--ink-muted);
}

.hero-cta {
  display: inline-block;
  padding: 0.65rem 2.25rem;
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 0.75rem;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--bg-elevated);
  background: var(--accent);
  border: 1px solid var(--accent);
  transition: background 0.2s ease, color 0.2s ease;
}

.hero-cta:hover {
  background: transparent;
  color: var(--accent);
}

/* Sections */
.section {
  padding: var(--space-2xl) 0;
  border-top: 1px solid var(--line);
}

.section-header {
  margin-bottom: var(--space-lg);
}

.section-eyebrow {
  display: block;
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 0.6875rem;
  letter-spacing: 0.4em;
  color: var(--accent);
  margin-bottom: var(--space-sm);
}

.section-title {
  margin: 0;
  font-family: var(--font-en);
  font-weight: 200;
  font-size: clamp(1.75rem, 3.5vw, 2.25rem);
  letter-spacing: 0.06em;
  color: var(--ink);
}

.section-title-zh {
  margin: var(--space-xs) 0 0;
  font-size: 0.9375rem;
  letter-spacing: 0.15em;
  color: var(--ink-soft);
}

.prose p {
  margin: 0 0 var(--space-md);
  font-size: 0.9375rem;
  line-height: 1.85;
  color: var(--ink-muted);
  text-align: justify;
  text-justify: inter-ideograph;
}

.prose p:last-child {
  margin-bottom: 0;
}

/* Research list */
.research-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line);
}

.research-list li {
  display: grid;
  grid-template-columns: 3.5rem 1fr;
  align-items: baseline;
  gap: var(--space-md);
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--line);
}

.research-list .num {
  font-family: var(--font-en);
  font-weight: 200;
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  color: var(--accent);
}

.research-list .text {
  font-size: 0.9375rem;
  color: var(--ink-muted);
  line-height: 1.7;
}

@media (min-width: 640px) {
  .research-list {
    grid-template-columns: 1fr 1fr;
    border-top: none;
    gap: 0 2rem;
  }

  .research-list li {
    border-bottom: 1px solid var(--line);
  }

  .research-list li:nth-last-child(-n + 2) {
    border-bottom-color: transparent;
  }
}

/* Tech grid */
.tech-grid {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.tech-card {
  background: var(--bg-elevated);
  padding: var(--space-lg) var(--space-md);
}

.tech-card h3 {
  margin: 0 0 var(--space-sm);
  font-size: 1rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  color: var(--ink);
}

.tech-card p {
  margin: 0;
  font-size: 0.875rem;
  line-height: 1.75;
  color: var(--ink-muted);
}

@media (min-width: 768px) {
  .tech-grid {
    grid-template-columns: 1fr 1fr;
  }
}

/* Academic */
.section-academic {
  background: var(--bg-elevated);
}

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

.academic-list li {
  position: relative;
  padding: var(--space-md) 0 var(--space-md) 1.5rem;
  font-size: 0.9375rem;
  color: var(--ink-muted);
  border-bottom: 1px solid var(--line);
  line-height: 1.7;
}

.academic-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 1.35rem;
  width: 6px;
  height: 1px;
  background: var(--accent);
}

.academic-list li:last-child {
  border-bottom: none;
}

/* Cooperation */
.section-cooperation {
  background: linear-gradient(180deg, var(--bg) 0%, #eef3f0 100%);
}

.coop-lead {
  font-weight: 400;
  color: var(--ink);
}

.coop-note {
  margin-top: var(--space-md);
  padding-top: var(--space-md);
  border-top: 1px solid var(--line-strong);
  color: var(--ink);
}

/* Footer */
.site-footer {
  padding: var(--space-xl) var(--space-sm);
  border-top: 1px solid var(--line);
  background: var(--ink);
  color: rgba(255, 255, 255, 0.65);
  text-align: center;
}

.footer-inner {
  max-width: 36rem;
}

.footer-name {
  margin: 0 0 var(--space-sm);
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 0.8125rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.9);
}

.footer-address,
.footer-copy {
  margin: 0.35rem 0;
  font-size: 0.8125rem;
  letter-spacing: 0.04em;
}

.footer-copy {
  margin-top: var(--space-md);
  color: rgba(255, 255, 255, 0.45);
}

[hidden] {
  display: none !important;
}

/* English UI: Latin typography & alignment */
body.lang-en .prose p,
body.lang-en .hero-tagline,
body.lang-en .hero-sub.zh,
body.lang-en .research-list .text,
body.lang-en .tech-card h3,
body.lang-en .tech-card p,
body.lang-en .academic-list li,
body.lang-en .cooperation-prose,
body.lang-en .footer-address,
body.lang-en .footer-copy {
  font-family: var(--font-en);
}

body.lang-en .prose p {
  text-align: start;
  text-justify: none;
  hyphens: auto;
}

body.lang-en .container.narrow {
  width: min(100% - 2.5rem, 46rem);
}