/* ===== CSS Variables ===== */
:root {
  --color-bg: #faf8f5;
  --color-surface: #ffffff;
  --color-text: #1a1a1a;
  --color-text-secondary: #555;
  --color-accent: #c0392b;
  --color-accent-dark: #96281b;
  --color-gold: #d4a843;
  --color-gold-light: #f0e6cc;
  --color-ink: #2c3e50;
  --color-border: #e0dcd5;
  --font-heading: 'Noto Serif SC', 'Georgia', serif;
  --font-body: 'Inter', 'Helvetica Neue', Arial, sans-serif;
  --max-width: 1200px;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0,0,0,0.06);
  --shadow-hover: 0 8px 40px rgba(0,0,0,0.12);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--color-accent); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-accent-dark); }

/* ===== Typography ===== */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.3;
  color: var(--color-ink);
}

h1 { font-size: clamp(2rem, 5vw, 3.2rem); }
h2 { font-size: clamp(1.5rem, 3.5vw, 2.2rem); }
h3 { font-size: clamp(1.2rem, 2.5vw, 1.6rem); }

p { margin-bottom: 1.2em; }

/* ===== Layout ===== */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 clamp(1rem, 4vw, 2rem);
}

/* ===== Header & Nav ===== */
.site-header {
  background: var(--color-ink);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 2px 12px rgba(0,0,0,0.15);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.8rem;
  padding-bottom: 0.8rem;
}

.site-logo {
  font-family: var(--font-heading);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-gold);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.site-logo .cn { font-size: 1.1rem; opacity: 0.8; }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.6rem;
  cursor: pointer;
  padding: 0.3rem;
}

.main-nav ul {
  list-style: none;
  display: flex;
  gap: 0.2rem;
}

.main-nav a {
  color: rgba(255,255,255,0.85);
  padding: 0.5rem 1rem;
  border-radius: 6px;
  font-size: 0.95rem;
  font-weight: 500;
  transition: all var(--transition);
  display: block;
  white-space: nowrap;
}

.main-nav a:hover,
.main-nav a.active {
  background: rgba(255,255,255,0.1);
  color: var(--color-gold);
}

/* ===== Hero Section ===== */
.hero {
  background: linear-gradient(135deg, var(--color-ink) 0%, #1a3a4a 50%, #2c1810 100%);
  color: #fff;
  padding: clamp(4rem, 10vw, 8rem) 0;
  position: relative;
  overflow: hidden;
  text-align: center;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 20% 50%, rgba(212,168,67,0.15) 0%, transparent 50%),
    radial-gradient(circle at 80% 30%, rgba(192,57,43,0.1) 0%, transparent 40%);
  pointer-events: none;
}

.hero-content { position: relative; z-index: 1; }

.hero h1 {
  color: #fff;
  margin-bottom: 0.3em;
  letter-spacing: 0.02em;
}

.hero .subtitle {
  font-size: clamp(1.1rem, 2.5vw, 1.4rem);
  color: var(--color-gold);
  font-family: var(--font-heading);
  margin-bottom: 1em;
  font-weight: 400;
}

.hero .lead {
  font-size: clamp(1rem, 1.8vw, 1.15rem);
  max-width: 700px;
  margin: 0 auto 2em;
  opacity: 0.9;
  line-height: 1.9;
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--color-accent);
  color: #fff;
  padding: 0.9rem 2rem;
  border-radius: 50px;
  font-weight: 600;
  font-size: 1.05rem;
  transition: all var(--transition);
  box-shadow: 0 4px 20px rgba(192,57,43,0.3);
}

.hero-cta:hover {
  background: var(--color-accent-dark);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 6px 28px rgba(192,57,43,0.4);
}

/* ===== Section Titles ===== */
.section-title {
  text-align: center;
  margin-bottom: 3rem;
}

.section-title h2 {
  position: relative;
  display: inline-block;
  padding-bottom: 0.6em;
}

.section-title h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-gold));
  border-radius: 2px;
}

.section-title p {
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 1em auto 0;
  font-size: 1.05rem;
}

/* ===== Invention Cards ===== */
.inventions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  padding: 4rem 0;
}

.invention-card {
  background: var(--color-surface);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}

.invention-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
}

.card-icon {
  height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  position: relative;
  overflow: hidden;
}

.card-icon::before {
  content: '';
  position: absolute;
  inset: 0;
  opacity: 0.08;
}

.card-icon.paper { background: linear-gradient(135deg, #f5f0e1, #ebe3d0); }
.card-icon.printing { background: linear-gradient(135deg, #e8d5b7, #d4c4a0); }
.card-icon.gunpowder { background: linear-gradient(135deg, #f0d5c8, #e8c4b0); }
.card-icon.compass { background: linear-gradient(135deg, #c8daf0, #b0c8e8); }

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

.card-body h3 {
  margin-bottom: 0.5em;
  font-size: 1.3rem;
}

.card-body .card-period {
  color: var(--color-gold);
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5em;
}

.card-body p {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  flex: 1;
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--color-accent);
  font-weight: 600;
  font-size: 0.95rem;
  margin-top: 1rem;
  transition: gap var(--transition);
}

.card-link:hover { gap: 0.8rem; }

/* ===== More Innovations Grid ===== */
.more-innovations {
  background: var(--color-surface);
  padding: 4rem 0;
}

.innovation-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1.5rem;
}

.innovation-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 1.2rem;
  border-radius: var(--radius);
  background: var(--color-bg);
  transition: all var(--transition);
}

.innovation-item:hover {
  background: var(--color-gold-light);
  transform: translateX(4px);
}

.innovation-item .icon {
  font-size: 2rem;
  flex-shrink: 0;
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-surface);
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.innovation-item h4 {
  font-size: 1rem;
  margin-bottom: 0.2em;
}

.innovation-item p {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin: 0;
}

/* ===== Timeline Section ===== */
.timeline-section { padding: 4rem 0; }

.timeline {
  position: relative;
  max-width: 800px;
  margin: 0 auto;
  padding-left: 2.5rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(to bottom, var(--color-accent), var(--color-gold), var(--color-accent));
  border-radius: 2px;
}

.timeline-item {
  position: relative;
  margin-bottom: 2.5rem;
  padding-left: 1.5rem;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -2.65rem;
  top: 0.4rem;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 3px solid var(--color-bg);
  box-shadow: 0 0 0 3px var(--color-accent);
}

.timeline-item .year {
  font-family: var(--font-heading);
  font-weight: 700;
  color: var(--color-accent);
  font-size: 1.1rem;
  margin-bottom: 0.3em;
}

.timeline-item h3 { font-size: 1.15rem; margin-bottom: 0.3em; }
.timeline-item p { color: var(--color-text-secondary); font-size: 0.95rem; margin: 0; }

/* ===== SEO Content Block ===== */
.seo-content {
  padding: 4rem 0;
  max-width: 900px;
  margin: 0 auto;
}

.seo-content h2 { margin-bottom: 1.5rem; text-align: center; }

.seo-content p {
  color: var(--color-text-secondary);
  font-size: 1rem;
  line-height: 1.9;
}

/* ===== Breadcrumb ===== */
.breadcrumb {
  padding: 1rem 0;
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

.breadcrumb a { color: var(--color-text-secondary); }
.breadcrumb a:hover { color: var(--color-accent); }
.breadcrumb span { margin: 0 0.5rem; opacity: 0.5; }

/* ===== Article Page ===== */
.article-hero {
  background: linear-gradient(135deg, var(--color-ink) 0%, #1a3a4a 100%);
  color: #fff;
  padding: clamp(3rem, 8vw, 6rem) 0;
  text-align: center;
}

.article-hero h1 { color: #fff; margin-bottom: 0.5em; }
.article-hero .meta {
  font-size: 0.95rem;
  opacity: 0.8;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.article-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 3rem;
  padding: 3rem 0;
  max-width: var(--max-width);
  margin: 0 auto;
  padding-left: clamp(1rem, 4vw, 2rem);
  padding-right: clamp(1rem, 4vw, 2rem);
}

.article-main { min-width: 0; }

.article-main h2 {
  margin: 2.5rem 0 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border);
}

.article-main h2:first-of-type { border-top: none; margin-top: 0; }

.article-main h3 { margin: 1.8rem 0 0.8rem; }

.article-main p {
  font-size: 1.05rem;
  line-height: 1.9;
}

.article-main ul, .article-main ol {
  margin: 1em 0 1.5em 1.5em;
  line-height: 1.8;
}

.article-main li { margin-bottom: 0.5em; }

.article-main blockquote {
  border-left: 4px solid var(--color-gold);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  background: var(--color-gold-light);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-style: italic;
  color: var(--color-text-secondary);
}

.article-main .highlight-box {
  background: linear-gradient(135deg, var(--color-gold-light), #f5efe0);
  border-radius: var(--radius);
  padding: 1.5rem 2rem;
  margin: 2rem 0;
  border-left: 4px solid var(--color-gold);
}

.article-main .highlight-box h4 {
  color: var(--color-accent);
  margin-bottom: 0.5em;
}

/* ===== Sidebar ===== */
.sidebar { position: sticky; top: 100px; align-self: start; }

.sidebar-widget {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow);
}

.sidebar-widget h3 {
  font-size: 1rem;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-gold-light);
}

.sidebar-widget ul {
  list-style: none;
}

.sidebar-widget li {
  margin-bottom: 0.5rem;
}

.sidebar-widget a {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  color: var(--color-text);
  font-size: 0.95rem;
  transition: all var(--transition);
}

.sidebar-widget a:hover,
.sidebar-widget a.active {
  background: var(--color-gold-light);
  color: var(--color-accent);
}

.sidebar-widget .related-card {
  display: flex;
  gap: 0.8rem;
  padding: 0.8rem;
  border-radius: 8px;
  background: var(--color-bg);
  margin-bottom: 0.8rem;
  transition: all var(--transition);
}

.sidebar-widget .related-card:hover {
  background: var(--color-gold-light);
}

.sidebar-widget .related-card .emoji {
  font-size: 1.8rem;
  flex-shrink: 0;
}

.sidebar-widget .related-card h4 {
  font-size: 0.9rem;
  margin-bottom: 0.2em;
}

.sidebar-widget .related-card p {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin: 0;
}

/* ===== Internal Links Section ===== */
.internal-links {
  background: var(--color-surface);
  padding: 3rem 0;
  border-top: 1px solid var(--color-border);
}

.internal-links .links-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
}

.internal-links .link-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.2rem;
  background: var(--color-bg);
  border-radius: var(--radius);
  transition: all var(--transition);
  border: 1px solid transparent;
}

.internal-links .link-card:hover {
  border-color: var(--color-gold);
  background: var(--color-gold-light);
  transform: translateY(-2px);
}

.internal-links .link-card .emoji { font-size: 2rem; }
.internal-links .link-card h4 { font-size: 1rem; margin-bottom: 0.2em; }
.internal-links .link-card p { font-size: 0.85rem; color: var(--color-text-secondary); margin: 0; }

/* ===== Footer ===== */
.site-footer {
  background: var(--color-ink);
  color: rgba(255,255,255,0.7);
  padding: 3rem 0 1.5rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 3rem;
  margin-bottom: 2rem;
}

.footer-about h3 { color: var(--color-gold); margin-bottom: 1em; font-size: 1.2rem; }
.footer-about p { font-size: 0.9rem; line-height: 1.7; }

.footer-links h4 { color: #fff; margin-bottom: 1em; font-size: 1rem; }
.footer-links ul { list-style: none; }
.footer-links li { margin-bottom: 0.5rem; }
.footer-links a { color: rgba(255,255,255,0.6); font-size: 0.9rem; }
.footer-links a:hover { color: var(--color-gold); }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 1.5rem;
  text-align: center;
  font-size: 0.85rem;
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .article-layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
  }

  .sidebar-widget { margin-bottom: 0; }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
}

@media (max-width: 768px) {
  .nav-toggle { display: block; }

  .main-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-ink);
    box-shadow: 0 8px 24px rgba(0,0,0,0.2);
    padding: 1rem;
  }

  .main-nav.open { display: block; }

  .main-nav ul {
    flex-direction: column;
    gap: 0.2rem;
  }

  .main-nav a {
    padding: 0.8rem 1rem;
    border-radius: 8px;
  }

  .inventions-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .hero { padding: 3rem 0; }
}

@media (max-width: 480px) {
  .invention-list { grid-template-columns: 1fr; }
  .internal-links .links-grid { grid-template-columns: 1fr; }
  .article-hero .meta { flex-direction: column; gap: 0.5rem; }
}

/* ===== Dark Mode (prefers-color-scheme) ===== */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #1a1816;
    --color-surface: #242220;
    --color-text: #e8e4de;
    --color-text-secondary: #a09888;
    --color-border: #3a3630;
    --color-ink: #f0ece4;
    --color-gold-light: #2a2520;
    --shadow: 0 4px 24px rgba(0,0,0,0.2);
    --shadow-hover: 0 8px 40px rgba(0,0,0,0.3);
  }
}

/* ===== Print Styles ===== */
@media print {
  .site-header, .site-footer, .sidebar, .nav-toggle { display: none; }
  .hero, .article-hero { background: #333; padding: 2rem 0; }
  body { font-size: 12pt; }
}