:root {
  --bg: #f4f6fb;
  --bg-elevated: #ffffff;
  --ink: #0f172a;
  --ink-soft: #334155;
  --muted: #64748b;
  --line: rgba(15, 23, 42, 0.08);
  --accent: #2563eb;
  --accent-soft: #dbeafe;
  --accent-glow: rgba(37, 99, 235, 0.18);
  --gradient-start: #eff6ff;
  --gradient-end: #f8fafc;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 12px 40px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 24px 64px rgba(15, 23, 42, 0.12);
  --radius-sm: 12px;
  --radius-md: 20px;
  --radius-lg: 28px;
  --radius-full: 999px;
  --header-h: 72px;
  --transition: 0.22s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(ellipse 80% 50% at 0% -10%, var(--gradient-start), transparent 55%),
    radial-gradient(ellipse 60% 40% at 100% 0%, rgba(219, 234, 254, 0.6), transparent 50%),
    var(--bg);
  color: var(--ink);
  font-family: "Inter", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

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

a:hover {
  color: #1d4ed8;
}

/* ── Header ── */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-h);
  background: rgba(244, 246, 251, 0.82);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px) saturate(1.4);
}

.nav {
  align-items: center;
  display: flex;
  height: 100%;
  justify-content: space-between;
  margin: 0 auto;
  max-width: 1140px;
  padding: 0 1.5rem;
}

.brand {
  color: var(--ink);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.brand:hover {
  color: var(--accent);
}

.nav-links {
  align-items: center;
  display: flex;
  gap: 0.25rem;
}

.nav-links a {
  border-radius: var(--radius-full);
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.45rem 0.85rem;
  transition: background var(--transition), color var(--transition);
}

.nav-links a:hover {
  background: rgba(37, 99, 235, 0.08);
  color: var(--accent);
}

.lang-switch {
  background: var(--accent-soft) !important;
  color: #1e40af !important;
  font-weight: 600 !important;
}

.lang-switch:hover {
  background: #bfdbfe !important;
  color: #1d4ed8 !important;
}

html[lang="zh"] body {
  font-family: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

/* ── Layout ── */

.section {
  margin: 0 auto;
  max-width: 1140px;
  padding: 5.5rem 1.5rem;
}

.section-heading {
  margin-bottom: 2.5rem;
  max-width: 640px;
}

.eyebrow {
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  margin: 0 0 0.6rem;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.15;
  margin: 0;
}

h1 {
  font-size: clamp(2.4rem, 5.5vw, 3.75rem);
}

h2 {
  font-size: clamp(1.75rem, 3.5vw, 2.5rem);
}

h3 {
  font-size: 1.2rem;
}

p {
  margin: 0;
}

/* ── Hero ── */

.hero {
  align-items: center;
  display: grid;
  gap: 3.5rem;
  grid-template-columns: 1.15fr 0.85fr;
  min-height: calc(100vh - var(--header-h));
  padding-bottom: 4rem;
  padding-top: 3rem;
}

.hero h1 {
  margin-bottom: 1.25rem;
}

.hero-lead {
  color: var(--ink-soft);
  font-size: 1.125rem;
  line-height: 1.7;
  max-width: 540px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2rem;
}

.button {
  align-items: center;
  border-radius: var(--radius-full);
  display: inline-flex;
  font-size: 0.925rem;
  font-weight: 600;
  gap: 0.4rem;
  padding: 0.75rem 1.35rem;
  transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
}

.button:hover {
  transform: translateY(-1px);
}

.button.primary {
  background: var(--accent);
  box-shadow: 0 4px 14px var(--accent-glow);
  color: #fff;
}

.button.primary:hover {
  background: #1d4ed8;
  box-shadow: 0 6px 20px var(--accent-glow);
  color: #fff;
}

.button.secondary {
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
}

.button.secondary:hover {
  border-color: rgba(37, 99, 235, 0.25);
  color: var(--accent);
}

/* ── Profile card ── */

.profile-card {
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  position: relative;
}

.profile-card::before {
  background: linear-gradient(135deg, var(--accent-soft), transparent 60%);
  content: "";
  height: 120px;
  left: 0;
  pointer-events: none;
  position: absolute;
  right: 0;
  top: 0;
}

.profile-photo-wrap {
  padding: 1.5rem 1.5rem 0;
  position: relative;
}

.profile-card img {
  aspect-ratio: 4 / 5;
  border-radius: var(--radius-md);
  object-fit: cover;
  width: 100%;
}

.photo-fallback {
  align-items: center;
  aspect-ratio: 4 / 5;
  background: linear-gradient(145deg, #2563eb, #1e3a8a);
  border-radius: var(--radius-md);
  color: #fff;
  display: none;
  font-size: 3.5rem;
  font-weight: 800;
  justify-content: center;
  letter-spacing: -0.06em;
  width: 100%;
}

.profile-meta {
  padding: 1.5rem;
}

.profile-meta h2 {
  font-size: 1.5rem;
  margin-bottom: 0.35rem;
}

.profile-meta .name-cn {
  color: var(--muted);
  font-size: 1rem;
  font-weight: 500;
}

.profile-meta .role-line {
  color: var(--muted);
  font-size: 0.925rem;
  margin-top: 0.5rem;
}

/* ── About highlights ── */

.about-grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 2.5rem;
}

.highlight-card {
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  padding: 1.35rem 1.5rem;
  transition: box-shadow var(--transition), transform var(--transition);
}

.highlight-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.highlight-card .label {
  color: var(--accent);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  margin-bottom: 0.5rem;
  text-transform: uppercase;
}

.highlight-card p {
  color: var(--ink-soft);
  font-size: 0.95rem;
  line-height: 1.55;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 2rem;
}

.skill-tag {
  background: var(--accent-soft);
  border-radius: var(--radius-full);
  color: #1e40af;
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.35rem 0.8rem;
}

/* ── Project cards ── */

.card-grid {
  display: grid;
  gap: 1.25rem;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.card {
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transition: box-shadow var(--transition), transform var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}

.card-image {
  aspect-ratio: 16 / 10;
  background: linear-gradient(135deg, #e2e8f0, #f1f5f9);
  overflow: hidden;
}

.card-image img {
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
  width: 100%;
}

.card:hover .card-image img {
  transform: scale(1.04);
}

.card-image.placeholder {
  align-items: center;
  background: linear-gradient(145deg, #e2e8f0 0%, #f1f5f9 50%, #e2e8f0 100%);
  display: flex;
  justify-content: center;
  position: relative;
}

.card-image.placeholder::before {
  background: radial-gradient(circle at 30% 40%, rgba(37, 99, 235, 0.08), transparent 60%);
  content: "";
  inset: 0;
  position: absolute;
}

.card-image.placeholder span {
  color: var(--muted);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.card-body {
  display: flex;
  flex: 1;
  flex-direction: column;
  padding: 1.35rem 1.5rem 1.5rem;
}

.tag {
  align-self: flex-start;
  background: var(--accent-soft);
  border-radius: var(--radius-full);
  color: #1e40af;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  margin-bottom: 0.75rem;
  padding: 0.3rem 0.65rem;
  text-transform: uppercase;
}

.card h3 {
  margin-bottom: 0.5rem;
}

.card p {
  color: var(--muted);
  flex: 1;
  font-size: 0.925rem;
  line-height: 1.6;
  margin-bottom: 1rem;
}

.card-link {
  align-items: center;
  color: var(--accent);
  display: inline-flex;
  font-size: 0.9rem;
  font-weight: 600;
  gap: 0.3rem;
}

.card-link::after {
  content: "→";
  transition: transform var(--transition);
}

.card:hover .card-link::after {
  transform: translateX(3px);
}

/* ── Writing ── */

.writing-list {
  display: grid;
  gap: 0.75rem;
}

.writing-item {
  align-items: start;
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
  display: grid;
  gap: 0.2rem;
  padding: 1.25rem 1.5rem;
  transition: box-shadow var(--transition), transform var(--transition);
}

.writing-item:hover {
  box-shadow: var(--shadow-md);
  color: var(--ink);
  transform: translateY(-2px);
}

.writing-item span {
  color: var(--accent);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.writing-item strong {
  font-size: 1.05rem;
}

.writing-item small {
  color: var(--muted);
  font-size: 0.9rem;
}

/* ── Contact strip ── */

.contact-strip {
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  justify-content: space-between;
  padding: 2rem 2.5rem;
}

.contact-section {
  padding-top: 2rem;
}

.contact-strip h2 {
  font-size: 1.5rem;
}

.contact-strip p {
  color: var(--muted);
  font-size: 0.95rem;
  margin-top: 0.35rem;
}

.contact-links {
  align-items: center;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* ── Footer ── */

.footer {
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.875rem;
  margin-top: 2rem;
  padding: 2.5rem 1.5rem 3rem;
  text-align: center;
}

/* ── Article / project detail ── */

.article {
  max-width: 820px;
}

.back-link {
  align-items: center;
  color: var(--muted);
  display: inline-flex;
  font-size: 0.9rem;
  font-weight: 600;
  gap: 0.3rem;
  margin-bottom: 1.5rem;
  transition: color var(--transition);
}

.back-link:hover {
  color: var(--accent);
}

.content-card {
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  padding: clamp(1.75rem, 4vw, 3rem);
}

.content-card h1 {
  font-size: clamp(2rem, 4.5vw, 2.75rem);
  margin-bottom: 1rem;
}

.content-card > p {
  color: var(--ink-soft);
  font-size: 1.05rem;
  line-height: 1.7;
}

.content-card h2 {
  font-size: 1.35rem;
  margin-top: 2.25rem;
}

.content-card h2:first-of-type {
  margin-top: 1.75rem;
}

.content-card ul {
  color: var(--ink-soft);
  margin: 0.75rem 0 0;
  padding-left: 1.25rem;
}

.content-card li + li {
  margin-top: 0.45rem;
}

.content-card li {
  line-height: 1.6;
}

.media-block {
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  margin: 1.75rem 0;
  overflow: hidden;
}

.media-block img,
.media-block video {
  width: 100%;
}

.media-caption {
  background: #f8fafc;
  color: var(--muted);
  font-size: 0.85rem;
  padding: 0.75rem 1rem;
}

.spec-table {
  border-collapse: collapse;
  font-size: 0.925rem;
  margin-top: 0.75rem;
  width: 100%;
}

.spec-table th,
.spec-table td {
  border-bottom: 1px solid var(--line);
  padding: 0.65rem 0.75rem;
  text-align: left;
}

.spec-table th {
  color: var(--muted);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.spec-table td:first-child {
  color: var(--ink-soft);
  font-weight: 600;
  width: 38%;
}

.external-link {
  align-items: center;
  display: inline-flex;
  font-weight: 600;
  gap: 0.3rem;
}

.reflection-box {
  background: #f8fafc;
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--ink-soft);
  font-size: 0.95rem;
  line-height: 1.65;
  margin-top: 2rem;
  padding: 1rem 1.25rem;
}

.content-card code {
  background: #f1f5f9;
  border-radius: 4px;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.88em;
  padding: 0.15em 0.4em;
}

/* ── Reveal animation ── */

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Responsive ── */

@media (max-width: 900px) {
  .hero,
  .card-grid,
  .about-grid {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: auto;
    padding-top: 2rem;
  }

  .profile-card {
    max-width: 380px;
  }

  .section {
    padding: 3.5rem 1.25rem;
  }

  .contact-strip {
    flex-direction: column;
    padding: 1.75rem;
  }
}

@media (max-width: 600px) {
  .nav {
    align-items: flex-start;
    flex-direction: column;
    height: auto;
    justify-content: center;
    padding: 0.85rem 1.25rem;
  }

  .site-header {
    height: auto;
  }

  .nav-links {
    flex-wrap: wrap;
    margin-top: 0.25rem;
  }
}