:root {
  --bg: #fafaf9;
  --surface: #ffffff;
  --surface-alt: #f5f4f1;
  --text: #1c1c1c;
  --muted: #5a5a5a;
  --muted-2: #8a8a8a;
  --border: #e5e5e3;
  --border-soft: #eeece7;
  --accent: #2d4a8a;
  --accent-hover: #1d3570;
  --code-bg: #f4f4f2;
  --sidebar-width: 260px;
  --content-max: 820px;
  --radius: 6px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1114;
    --surface: #171a1f;
    --surface-alt: #13161a;
    --text: #e8e8e6;
    --muted: #a8a8a3;
    --muted-2: #6e6e6a;
    --border: #2a2e34;
    --border-soft: #1e2228;
    --accent: #7fa8f0;
    --accent-hover: #a5c3f7;
    --code-bg: #1f232a;
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s ease;
}
a:hover { color: var(--accent-hover); text-decoration: underline; }
code, .mono { font-family: 'JetBrains Mono', Menlo, monospace; font-size: 0.9em; }

/* ==================== Sidebar ==================== */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: var(--surface);
  border-right: 1px solid var(--border);
  padding: 2.2rem 1.6rem 1.6rem;
  display: flex;
  flex-direction: column;
  z-index: 20;
  transition: transform 0.28s ease;
}

.sidebar-brand {
  margin-bottom: 2.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-soft);
}
.brand-name {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text);
  line-height: 1.2;
}
.brand-zh {
  font-weight: 500;
  color: var(--muted);
  font-size: 0.85em;
  margin-left: 0.3rem;
}
.brand-tagline {
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.45;
  margin-top: 0.55rem;
}

.sidebar-nav {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  flex: 1;
}
.sidebar-nav a {
  display: flex;
  align-items: baseline;
  gap: 0.9rem;
  padding: 0.6rem 0.75rem;
  border-radius: var(--radius);
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 500;
  border-left: 2px solid transparent;
  transition: all 0.15s ease;
  text-decoration: none;
}
.sidebar-nav a:hover {
  color: var(--text);
  background: var(--surface-alt);
  text-decoration: none;
}
.sidebar-nav a.active {
  color: var(--accent);
  background: var(--surface-alt);
  border-left-color: var(--accent);
  padding-left: 0.65rem;
}
.sidebar-nav .nav-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--muted-2);
  min-width: 1.3rem;
}
.sidebar-nav a.active .nav-num { color: var(--accent); }
.sidebar-nav .nav-label { font-weight: 500; }

.sidebar-footer {
  margin-top: auto;
  padding-top: 1.4rem;
  border-top: 1px solid var(--border-soft);
}
.sidebar-resumes {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-bottom: 1rem;
}
.sidebar-resumes a {
  font-size: 0.82rem;
  color: var(--muted);
  padding: 0.3rem 0;
}
.sidebar-resumes a:hover {
  color: var(--accent);
  text-decoration: none;
}
.sidebar-contact {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.sidebar-contact a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 0.72rem;
  font-weight: 600;
  font-family: 'JetBrains Mono', monospace;
  color: var(--muted);
}
.sidebar-contact a:hover {
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
}

/* ==================== Menu toggle (mobile) ==================== */
.menu-toggle {
  display: none;
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: 30;
  width: 40px;
  height: 40px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 4px;
  padding: 0;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
}
.menu-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
}

.sidebar-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.35);
  z-index: 19;
  opacity: 0;
  transition: opacity 0.25s ease;
}
.sidebar-backdrop.visible {
  display: block;
  opacity: 1;
}

/* ==================== Main content ==================== */
.content {
  margin-left: var(--sidebar-width);
  padding: 3.5rem 3rem 4rem;
  min-height: 100vh;
}

/* ==================== Tabs ==================== */
.tab {
  display: none;
  max-width: var(--content-max);
  margin: 0 auto;
}
.tab.active {
  display: block;
  animation: fadeSlideIn 0.28s ease;
}

@keyframes fadeSlideIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==================== Hero (home tab) ==================== */
.hero {
  padding-bottom: 2.5rem;
  margin-bottom: 2.5rem;
  border-bottom: 1px solid var(--border);
}
.hero h1 {
  font-size: clamp(2rem, 4.5vw, 2.7rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 0.3rem;
  line-height: 1.15;
}
.hero h1 .zh {
  font-weight: 500;
  color: var(--muted);
  font-size: 0.55em;
  margin-left: 0.4rem;
  vertical-align: 0.15em;
}
.hero-tagline {
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--text);
  margin: 0.2rem 0 0.9rem;
}
.hero-tagline .sep { color: var(--muted-2); margin: 0 0.5rem; }
.hero-sub {
  color: var(--muted);
  font-size: 1rem;
  max-width: 680px;
  margin: 0 0 1.6rem;
}
.hero-sub strong { color: var(--text); font-weight: 600; }

.cta {
  display: flex;
  gap: 0.8rem;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.65rem 1.1rem;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  transition: all 0.15s ease;
  text-decoration: none;
}
.btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
  transform: translateY(-1px);
}
.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.btn-primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: #fff;
}
.btn .arrow { font-size: 1em; opacity: 0.9; }

/* ==================== Tab header (non-home tabs) ==================== */
.tab-header {
  margin-bottom: 2.5rem;
  padding-bottom: 1.2rem;
  border-bottom: 1px solid var(--border);
}
.tab-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  color: var(--accent);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  margin: 0 0 0.55rem;
  font-weight: 600;
}
.tab-header h1 {
  font-size: clamp(1.8rem, 3.8vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0;
  line-height: 1.15;
}
.tab-subtitle {
  color: var(--muted);
  font-size: 1rem;
  margin: 0.55rem 0 0;
}

/* ==================== Section block (home tab) ==================== */
.section-block {
  margin-bottom: 3rem;
}
.section-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin: 0 0 1.3rem;
  padding-bottom: 0.55rem;
  border-bottom: 1px solid var(--border);
  letter-spacing: -0.01em;
  display: flex;
  align-items: baseline;
  gap: 0.8rem;
}
.section-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  color: var(--muted-2);
  font-weight: 500;
}

/* ==================== About subheadings (inside story tabs) ==================== */
.about-subhead {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
  margin: 2rem 0 0.7rem;
  letter-spacing: -0.005em;
}
.about-subhead::before {
  content: "▸ ";
  color: var(--accent);
  font-weight: 400;
}

/* ==================== Prose ==================== */
.prose {
  color: var(--muted);
  margin: 0 0 1rem;
  line-height: 1.7;
}
.prose strong { color: var(--text); font-weight: 600; }
.prose em { color: var(--text); font-style: italic; }
.prose code {
  background: var(--code-bg);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  font-size: 0.88em;
}

.prose-list {
  margin: 0 0 1rem;
  padding-left: 1.3rem;
  color: var(--muted);
}
ol.prose-list { list-style: decimal; }
ol.prose-list > li { margin-bottom: 0.9rem; }
ul.prose-list > li { margin-bottom: 0.6rem; }
.prose-list li { line-height: 1.65; }
.prose-list li strong { color: var(--text); font-weight: 600; }
.prose-list li em { color: var(--text); font-style: italic; }
.prose-list li code {
  background: var(--code-bg);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  font-size: 0.88em;
}
.prose-list li .cite {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85em;
  color: var(--accent);
  white-space: nowrap;
}
.prose-list li .stack-meta {
  color: var(--muted-2);
  font-size: 0.88em;
  font-style: normal;
  margin-left: 0.2rem;
}

.prose-sublist {
  margin: 0.45rem 0 0.4rem;
  padding-left: 1.3rem;
  list-style: disc;
}
.prose-sublist li {
  margin-bottom: 0.4rem;
  color: var(--muted);
  font-size: 0.95em;
  line-height: 1.55;
}
.prose-sublist li strong { color: var(--text); font-weight: 600; }
.prose-sublist li em { color: var(--text); font-style: italic; }
.prose-sublist li code {
  background: var(--code-bg);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  font-size: 0.88em;
}

/* ==================== Experience entries ==================== */
.entry {
  margin-bottom: 2rem;
}
.entry-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.1rem;
}
.entry h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 0;
  letter-spacing: -0.005em;
}
.entry h3 .muted { color: var(--muted); font-weight: 400; }
.when {
  font-size: 0.85rem;
  color: var(--muted-2);
  font-family: 'JetBrains Mono', monospace;
  white-space: nowrap;
}
.role {
  font-size: 0.9rem;
  color: var(--muted);
  margin: 0.1rem 0 0.6rem;
}
.role em { color: var(--text); font-style: italic; font-weight: 500; }
.entry ul {
  margin: 0.3rem 0 0;
  padding-left: 1.2rem;
}
.entry ul li {
  margin-bottom: 0.5rem;
  color: var(--muted);
}
.entry ul li strong { color: var(--text); font-weight: 600; }
.entry ul li em { color: var(--text); }

/* ==================== Publications grid ==================== */
.pub-grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: 1fr;
  margin: 1rem 0 1.5rem;
}
@media (min-width: 760px) {
  .pub-grid { grid-template-columns: 1fr 1fr; }
}
.pub {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.pub:hover { border-color: var(--accent); transform: translateY(-2px); }
.pub-title {
  font-weight: 600;
  color: var(--text);
  margin: 0 0 0.35rem;
  font-size: 0.98rem;
  line-height: 1.35;
}
.pub-meta {
  font-size: 0.85rem;
  color: var(--muted);
  margin: 0;
}
.pub-meta strong { color: var(--text); }
.pub-meta .cite {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  color: var(--accent);
}
.pub-cta {
  margin-top: 1.2rem;
  font-size: 0.92rem;
  color: var(--muted);
}

/* ==================== Preview cards (home overview) ==================== */
.preview-grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: 1fr;
}
@media (min-width: 720px) {
  .preview-grid { grid-template-columns: 1fr 1fr; }
}
.preview-card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.2rem 1.3rem;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease;
}
.preview-card:hover {
  border-color: var(--accent);
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(45, 74, 138, 0.08);
}
.preview-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin: 0 0 0.35rem;
  font-weight: 600;
}
.preview-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.005em;
  line-height: 1.3;
}
.preview-card .preview-desc {
  color: var(--muted);
  font-size: 0.92rem;
  margin: 0 0 0.7rem;
  line-height: 1.55;
}
.preview-card .preview-desc em { color: var(--text); font-style: italic; }
.preview-card .preview-cta {
  color: var(--accent);
  font-size: 0.88rem;
  font-weight: 500;
  margin: 0;
}
.preview-card:hover .preview-cta { color: var(--accent-hover); }

/* ==================== Skills ==================== */
.skills-grid {
  display: grid;
  gap: 1rem 1.8rem;
  grid-template-columns: 1fr;
}
@media (min-width: 720px) {
  .skills-grid { grid-template-columns: 1fr 1fr; }
}
.skills-grid h4 {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  margin: 0 0 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.skills-grid p {
  margin: 0;
  color: var(--muted);
  font-size: 0.93rem;
  line-height: 1.55;
}

/* ==================== Contact links row ==================== */
.links {
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem 1.6rem;
  font-size: 0.92rem;
  margin-top: 1rem;
}
.links a {
  color: var(--muted);
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
}
.links a:hover { color: var(--accent); text-decoration: none; }
.links .icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.4rem;
  height: 1.4rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: 0.72rem;
  font-weight: 600;
  font-family: 'JetBrains Mono', monospace;
  color: var(--muted);
}
.links a:hover .icon { border-color: var(--accent); color: var(--accent); }

/* ==================== Footer ==================== */
.footer {
  max-width: var(--content-max);
  margin: 4rem auto 0;
  padding: 1.5rem 0;
  border-top: 1px solid var(--border-soft);
  text-align: center;
  color: var(--muted-2);
  font-size: 0.82rem;
}
.footer p { margin: 0; }

/* ==================== Responsive ==================== */
@media (max-width: 900px) {
  :root { --sidebar-width: 240px; }

  .sidebar {
    transform: translateX(-100%);
    box-shadow: 2px 0 14px rgba(0, 0, 0, 0.08);
  }
  .sidebar.open {
    transform: translateX(0);
  }

  .content {
    margin-left: 0;
    padding: 4.5rem 1.4rem 3rem;
  }

  .menu-toggle {
    display: inline-flex;
  }

  body.sidebar-open { overflow: hidden; }

  .hero { padding-bottom: 1.8rem; margin-bottom: 2rem; }
  .tab-header { margin-bottom: 2rem; }
  .entry-head { flex-direction: column; align-items: flex-start; gap: 0.1rem; }
  .when { font-size: 0.8rem; }
  .cta { flex-direction: column; align-items: stretch; }
  .btn { justify-content: center; }
}

@media (max-width: 520px) {
  .content { padding: 4rem 1.1rem 2.5rem; }
  .hero-tagline { font-size: 1rem; }
  .hero-tagline .sep { display: block; margin: 0.2rem 0; }
}