:root {
  color-scheme: dark;
  --bg: #0B0D11;
  --panel: rgba(18, 22, 30, 0.75);
  --panel-solid: #12151E;
  --text: #F3F4F6;
  --text-secondary: #D1D5DB;
  --muted: #9CA3AF;
  --accent: #FF526E;
  --brand-red: #FF2442;
  --line: rgba(255, 255, 255, 0.09);
  --line-strong: rgba(255, 255, 255, 0.16);
  --card-glow: rgba(255, 36, 66, 0.15);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
  -webkit-tap-highlight-color: transparent;
}

body {
  margin: 0;
  background-color: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 1rem;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

::selection {
  background: var(--brand-red);
  color: #FFFFFF;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

a:hover {
  color: #FFA3B5;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  top: -5rem;
  left: 1rem;
  padding: 0.6rem 1.2rem;
  background: var(--bg);
  border: 1px solid var(--brand-red);
  border-radius: 0.5rem;
  color: #FFFFFF;
  font-weight: 600;
  z-index: 100;
  transition: top 0.2s ease;
}

.skip-link:focus {
  top: 1rem;
}

/* Site Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(11, 13, 17, 0.88);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  max-width: 1120px;
  margin: auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  color: #FFFFFF;
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.brand img {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  box-shadow: 0 4px 12px rgba(255, 36, 66, 0.25);
  transition: transform 0.2s ease;
}

.brand:hover img {
  transform: scale(1.05);
}

.brand span span {
  color: var(--brand-red);
}

.site-nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
  font-size: 0.875rem;
  font-weight: 500;
}

.site-nav a {
  color: var(--muted);
  text-decoration: none;
  padding: 0.35rem 0.65rem;
  border-radius: 0.5rem;
  transition: color 0.2s ease, background-color 0.2s ease;
}

.site-nav a:hover {
  color: #FFFFFF;
  background: rgba(255, 255, 255, 0.05);
}

.site-nav a[aria-current="page"] {
  color: #FFFFFF;
  background: rgba(255, 36, 66, 0.15);
  border: 1px solid rgba(255, 36, 66, 0.3);
  font-weight: 600;
}

/* Main Article Container */
main {
  max-width: 820px;
  margin: auto;
  padding: 2.5rem 1.5rem 5rem;
}

.breadcrumbs {
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: #FFFFFF;
  text-decoration: underline;
}

.breadcrumbs span[aria-current="page"] {
  color: var(--text-secondary);
}

.eyebrow {
  display: inline-block;
  color: var(--brand-red);
  background: rgba(255, 36, 66, 0.1);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  border: 1px solid rgba(255, 36, 66, 0.2);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

h1 {
  font-size: clamp(2.2rem, 5vw, 3.25rem);
  line-height: 1.15;
  letter-spacing: -0.03em;
  font-weight: 850;
  color: #FFFFFF;
  margin: 0.5rem 0 1rem;
}

.lead {
  font-size: 1.15rem;
  line-height: 1.6;
  color: #D1D5DB;
  margin: 0 0 1.25rem;
}

.byline {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--muted);
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--line);
}

.byline a {
  color: var(--text-secondary);
  text-decoration: none;
}

.byline a:hover {
  color: #FFFFFF;
  text-decoration: underline;
}

h2 {
  font-size: clamp(1.4rem, 3.5vw, 1.85rem);
  line-height: 1.3;
  letter-spacing: -0.02em;
  color: #FFFFFF;
  font-weight: 750;
  margin-top: 3.5rem;
  margin-bottom: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
}

h3 {
  font-size: 1.2rem;
  line-height: 1.4;
  color: #FFFFFF;
  font-weight: 700;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

p, li {
  color: var(--text-secondary);
}

p {
  margin: 1.1rem 0;
}

li + li {
  margin-top: 0.65rem;
}

strong {
  color: #FFFFFF;
  font-weight: 600;
}

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.88em;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 0.35rem;
  padding: 0.15rem 0.4rem;
  color: #FFA3B5;
}

/* Callouts & TOC */
.toc, .callout {
  padding: 1.35rem 1.65rem;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 1rem;
  margin: 2rem 0;
  box-shadow: 0 8px 24px -6px rgba(0, 0, 0, 0.4);
}

.toc {
  background: rgba(18, 22, 30, 0.5);
  border-left: 3px solid var(--accent);
}

.toc strong {
  display: block;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: #FFFFFF;
  margin-bottom: 0.75rem;
}

.toc ol {
  margin: 0;
  padding-left: 1.25rem;
}

.toc li {
  margin: 0.4rem 0;
}

.toc a {
  color: var(--text-secondary);
  text-decoration: none;
}

.toc a:hover {
  color: var(--accent);
  text-decoration: underline;
}

.callout {
  border-left: 3px solid var(--brand-red);
  background: linear-gradient(135deg, rgba(255, 36, 66, 0.08) 0%, rgba(18, 22, 30, 0.7) 100%);
}

.callout > :first-child, .toc > :first-child {
  margin-top: 0;
}

.callout > :last-child, .toc > :last-child {
  margin-bottom: 0;
}

/* Tables */
.table-scroll {
  overflow-x: auto;
  margin: 2rem 0;
  border-radius: 0.85rem;
  border: 1px solid var(--line);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.925rem;
  text-align: left;
}

th, td {
  padding: 0.95rem 1.15rem;
  border-bottom: 1px solid var(--line);
  vertical-align: middle;
}

th {
  background: #141822;
  color: #FFFFFF;
  font-weight: 700;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

tr:last-child td {
  border-bottom: none;
}

tr:hover td {
  background: rgba(255, 255, 255, 0.02);
}

td:first-child {
  font-weight: 600;
  color: #FFFFFF;
}

/* Blockquotes */
blockquote {
  margin: 1.5rem 0;
  padding: 1rem 1.4rem;
  border-left: 3px solid var(--brand-red);
  background: rgba(255, 36, 66, 0.05);
  border-radius: 0 0.75rem 0.75rem 0;
}

blockquote p {
  margin: 0.3rem 0;
  font-style: italic;
  color: #F3F4F6;
}

/* Slang Term Cards */
.term {
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--line);
}

.term h3 {
  font-size: 1.35rem;
  color: #FFFFFF;
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  margin-top: 0;
  margin-bottom: 0.65rem;
}

.pinyin {
  color: var(--muted);
  font-size: 0.95rem;
  font-family: ui-monospace, Menlo, Monaco, monospace;
  font-weight: 400;
}

.fine-print {
  font-size: 0.85rem;
  color: var(--muted);
  line-height: 1.6;
}

/* B2B In-Guide Conversion Banner */
.guide-cta {
  margin: 3.5rem 0 2rem;
  padding: 1.75rem 2rem;
  border-radius: 1.25rem;
  background: linear-gradient(135deg, rgba(255, 36, 66, 0.12) 0%, rgba(18, 22, 30, 0.85) 100%);
  border: 1px solid rgba(255, 36, 66, 0.3);
  box-shadow: 0 12px 30px -8px rgba(0, 0, 0, 0.5), 0 0 20px -5px var(--card-glow);
}

.guide-cta h3 {
  margin-top: 0;
  color: #FFFFFF;
  font-size: 1.25rem;
  font-weight: 800;
}

.guide-cta p {
  color: var(--text-secondary);
  font-size: 0.925rem;
  margin: 0.5rem 0 1.25rem;
  line-height: 1.6;
}

.guide-cta-btn {
  display: inline-block;
  background: linear-gradient(135deg, #FF2442 0%, #FF526E 100%);
  color: #FFFFFF !important;
  font-size: 0.875rem;
  font-weight: 700;
  padding: 0.65rem 1.4rem;
  border-radius: 0.75rem;
  text-decoration: none !important;
  box-shadow: 0 4px 14px rgba(255, 36, 66, 0.35);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.guide-cta-btn:hover {
  opacity: 0.92;
  transform: translateY(-1px);
}

/* Related Guides */
.related {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.related a {
  padding: 1.4rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  text-decoration: none;
  background: var(--panel);
  color: #FFFFFF;
  font-weight: 700;
  font-size: 1.05rem;
  transition: border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
}

.related a:hover {
  border-color: rgba(255, 36, 66, 0.4);
  transform: translateY(-2px);
  box-shadow: 0 10px 24px -6px rgba(0, 0, 0, 0.5);
}

.related small {
  display: block;
  color: var(--accent);
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-top: 0.5rem;
}

/* Site Footer */
.site-footer {
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.85rem;
  background: #07080B;
}

.site-footer a {
  color: var(--text-secondary);
}

.site-footer a:hover {
  color: #FFFFFF;
}

@media (max-width: 640px) {
  .header-inner {
    padding: 0.85rem 1rem;
    gap: 0.75rem;
  }
  .site-nav {
    gap: 0.35rem 0.75rem;
    font-size: 0.825rem;
  }
  main {
    padding: 1.75rem 1rem 4rem;
  }
  .related {
    grid-template-columns: 1fr;
  }
  th, td {
    padding: 0.75rem 0.85rem;
  }
  .guide-cta {
    padding: 1.25rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition-duration: 0.01ms !important; }
}