/* === Reset === */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* === Design Tokens === */
:root {
  --color-text: #1a1a2e;
  --color-text-secondary: #4a4a6a;
  --color-bg: #faf9f6;
  --color-accent: #c44536;
  --color-success: #2d6a4f;
  --color-border: #e8e4df;
  --color-card-bg: #f5f2ed;

  --font-en: 'Inter', system-ui, sans-serif;
  --font-zh: 'Noto Sans SC', sans-serif;

  --max-width: 720px;
  --section-gap: 80px;
  --content-padding: 24px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-zh), var(--font-en);
  font-weight: 400;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--content-padding);
}

section {
  padding: var(--section-gap) 0;
  border-bottom: 1px solid var(--color-border);
}

section:last-of-type {
  border-bottom: none;
}

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

a:hover {
  opacity: 0.7;
}

/* === Hero === */
#hero {
  text-align: center;
  padding-top: 120px;
  padding-bottom: 60px;
  border-bottom: none;
}

.hero-avatar img {
  width: 96px;
  height: 96px;
  border-radius: 50%;
  object-fit: cover;
  background: var(--color-border);
}

.hero-name {
  font-family: var(--font-en);
  font-size: 2rem;
  font-weight: 700;
  margin-top: 20px;
  color: var(--color-text);
}

.hero-title {
  font-size: 1rem;
  color: var(--color-text-secondary);
  margin-top: 8px;
}

.hero-tagline {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-top: 12px;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.6;
}

/* Language toggle */
.hero-lang-toggle {
  margin-top: 24px;
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.lang-btn {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text-secondary);
  font-size: inherit;
  font-family: inherit;
  padding: 2px 4px;
  transition: color 0.2s;
}

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

.lang-btn.active {
  color: var(--color-accent);
  font-weight: 600;
}

.lang-divider {
  color: var(--color-border);
}

/* Bilingual visibility — default Chinese */
html[lang="zh"] [lang="en"] { display: none; }

html[lang="en"] [lang="zh"] { display: none; }
html[lang="en"] [lang="en"], html[lang="zh"] [lang="zh"] { display: inline; }
/* block / list-item / table-row overrides */
html[lang="en"] [lang="en"].block, html[lang="zh"] [lang="zh"].block { display: block; }
html[lang="en"] li[lang="en"], html[lang="zh"] li[lang="zh"] { display: list-item; }
html[lang="en"] tr[lang="en"], html[lang="zh"] tr[lang="zh"] { display: table-row; }
html[lang="en"] td[lang="en"], html[lang="zh"] td[lang="zh"] { display: table-cell; }

/* === Project Detail Pages (shared) === */
.project-detail { max-width: 720px; margin: 0 auto; padding: 0 24px 64px; }
.back-link { display: inline-block; margin: 28px 0 20px; font-size: 0.85rem; color: var(--color-text-secondary); }
.back-link:hover { color: var(--color-accent); }
.project-hero { padding-bottom: 32px; border-bottom: 1px solid var(--color-border); }
.project-hero h1 { font-size: 1.75rem; font-weight: 700; margin-bottom: 6px; }
.project-meta { font-size: 0.85rem; color: var(--color-text-secondary); margin-bottom: 16px; }
.metrics-row { display: flex; gap: 32px; margin: 28px 0; }
.metric-item { text-align: center; }
.metric-value { font-family: var(--font-en); font-size: 2rem; font-weight: 700; color: var(--color-accent); }
.metric-label { font-size: 0.78rem; color: var(--color-text-secondary); margin-top: 4px; }
.narrative { padding-top: 32px; }
.narrative h2 { font-size: 0.75rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--color-text-secondary); margin: 28px 0 10px; }
.narrative p { font-size: 0.95rem; line-height: 1.75; color: var(--color-text); margin-bottom: 16px; }
.detail-tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 32px; padding-top: 24px; border-top: 1px solid var(--color-border); }
@media (max-width: 480px) { .metrics-row { gap: 16px; } .metric-value { font-size: 1.5rem; } .project-hero h1 { font-size: 1.35rem; } }

/* === Section Titles === */
.section-title {
  font-family: var(--font-en);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  margin-bottom: 32px;
}

/* === Career Timeline === */
.timeline {
  position: relative;
  padding-left: 28px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 5px;
  top: 4px;
  bottom: 4px;
  width: 1px;
  background: var(--color-border);
}

.timeline-item {
  position: relative;
  margin-bottom: 40px;
}

.timeline-item:last-child {
  margin-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: -28px;
  top: 6px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 2px solid var(--color-accent);
}

.timeline-item:first-child .timeline-dot {
  background: var(--color-accent);
}

.timeline-date {
  font-family: var(--font-en);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: 4px;
}

.timeline-role {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text);
}

.timeline-company {
  font-family: var(--font-en);
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-top: 2px;
}

.timeline-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin-top: 8px;
  line-height: 1.6;
  max-width: 560px;
}

/* === Selected Projects === */
.project-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.project-card {
  display: block;
  background: var(--color-card-bg);
  border: 1px solid transparent;
  border-radius: 8px;
  padding: 24px;
  color: var(--color-text);
  transition: border-color 0.2s, transform 0.2s;
}

.project-card:hover {
  border-color: var(--color-border);
  transform: translateY(-2px);
}

.project-metric {
  font-family: var(--font-en);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: 8px;
}

.project-name {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.project-summary {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
  margin-bottom: 12px;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  font-size: 0.72rem;
  padding: 2px 10px;
  border-radius: 100px;
  background: var(--color-bg);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

/* === Skills === */
.skill-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.skill-tag {
  font-size: 0.85rem;
  padding: 6px 16px;
  border-radius: 100px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  color: var(--color-text);
  transition: border-color 0.2s, color 0.2s;
}

.skill-tag:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* === Latest Insights === */
.insight-list {
  list-style: none;
}

.insight-item {
  border-bottom: 1px solid var(--color-border);
}

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

.insight-link {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 14px 0;
  color: var(--color-text);
  gap: 16px;
}

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

.insight-title {
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s;
}

.insight-date {
  font-family: var(--font-en);
  font-size: 0.78rem;
  color: var(--color-text-secondary);
  flex-shrink: 0;
}

/* === Header / Navigation === */
#site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(250, 249, 246, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--content-padding);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 52px;
}

.nav-logo {
  font-family: var(--font-en);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  letter-spacing: 0.04em;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 28px;
}

.nav-links a {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  font-weight: 500;
  transition: color 0.2s;
}

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

/* Hamburger (mobile only — hidden on desktop) */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.hamburger span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--color-text);
  transition: transform 0.2s, opacity 0.2s;
}

/* === Footer === */
#site-footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px var(--content-padding);
  text-align: center;
}

.footer-text {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

/* === Scroll Reveal === */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* Stagger sections slightly */
#projects.reveal { transition-delay: 0.05s; }
#skills.reveal  { transition-delay: 0.1s; }
#insights.reveal { transition-delay: 0.15s; }

/* === Mobile Navigation === */
@media (max-width: 640px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 52px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    gap: 0;
    padding: 12px 0;
    box-shadow: 0 4px 12px rgba(0,0,0,0.04);
  }

  .nav-links.nav-open {
    display: flex;
  }

  .nav-links li {
    text-align: center;
  }

  .nav-links a {
    display: block;
    padding: 12px var(--content-padding);
    font-size: 0.95rem;
  }

  .hamburger {
    display: flex;
  }
}

/* === Responsive — Tablet (768px) === */
@media (max-width: 768px) {
  :root {
    --section-gap: 60px;
  }

  .hero-name {
    font-size: 1.65rem;
  }

  .project-cards {
    grid-template-columns: 1fr;
  }

  .timeline-desc {
    max-width: 100%;
  }
}

/* === Responsive — Mobile (375px-480px) === */
@media (max-width: 480px) {
  :root {
    --section-gap: 48px;
    --content-padding: 18px;
  }

  #hero {
    padding-top: 90px;
    padding-bottom: 40px;
  }

  .hero-name {
    font-size: 1.5rem;
  }

  .hero-title {
    font-size: 0.9rem;
  }

  .hero-tagline {
    font-size: 0.85rem;
  }

  .section-title {
    font-size: 0.7rem;
    margin-bottom: 24px;
  }

  .timeline {
    padding-left: 22px;
  }

  .timeline-dot {
    left: -22px;
    width: 9px;
    height: 9px;
  }

  .timeline-role {
    font-size: 1rem;
  }

  .timeline-desc {
    font-size: 0.82rem;
  }

  .project-metric {
    font-size: 1.4rem;
  }

  .skill-cloud {
    gap: 8px;
  }

  .skill-tag {
    font-size: 0.78rem;
    padding: 5px 12px;
  }

  .insight-title {
    font-size: 0.85rem;
  }

  .insight-date {
    font-size: 0.72rem;
  }
}