:root {
  --color-primary: #b91c1c;
  --color-primary-dark: #991b1b;
  --color-secondary: #dc2626;
  --color-gold: #facc15;
  --color-gold-dark: #eab308;
  --color-dark: #111827;
  --color-dark-soft: #1f2937;
  --color-bg: #f8fafc;
  --color-bg-card: #ffffff;
  --color-text: #1e293b;
  --color-text-muted: #64748b;
  --color-text-light: #94a3b8;
  --color-border: #e2e8f0;
  --color-border-strong: #cbd5e1;
  --font-sans: "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  --font-serif: Georgia, "Times New Roman", serif;
  --font-mono: "Cascadia Code", Consolas, monospace;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --shadow-sm: 0 1px 3px rgba(17, 24, 39, 0.06);
  --shadow-md: 0 4px 16px rgba(17, 24, 39, 0.08);
  --shadow-lg: 0 12px 32px rgba(17, 24, 39, 0.12);
  --shadow-card: 0 2px 8px rgba(185, 28, 28, 0.06);
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --max-content: 950px;
  --max-wide: 950px;
  --header-h: 70px;
  --toc-width: 240px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.78;
  min-height: 100vh;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

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

a:hover {
  color: var(--color-secondary);
}

a:focus-visible {
  outline: 2px solid var(--color-gold);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  top: -100%;
  left: 16px;
  background: var(--color-primary);
  color: #fff;
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  z-index: 9999;
  font-weight: 600;
}

.skip-link:focus {
  top: 16px;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-h);
  box-shadow: var(--shadow-sm);
}

.site-header__inner {
  max-width: var(--max-wide);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 1.125rem;
  color: var(--color-dark);
  letter-spacing: -0.02em;
}

.site-logo__badge {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #fff;
  font-size: 0.6875rem;
  font-weight: 800;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  letter-spacing: 0.04em;
}

.site-nav {
  display: flex;
  gap: 4px;
}

.site-nav a {
  color: var(--color-text-muted);
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
}

.site-nav a:hover {
  color: var(--color-primary);
  background: rgba(185, 28, 28, 0.06);
}

/* Breadcrumb */
.breadcrumb-wrap {
  max-width: var(--max-wide);
  margin: 0 auto;
  padding: 18px 24px 0;
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  list-style: none;
  font-size: 0.8125rem;
}

.breadcrumb__item {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--color-text-light);
}

.breadcrumb__item:not(:last-child)::after {
  content: "/";
  color: var(--color-border-strong);
}

.breadcrumb__item a {
  color: var(--color-text-muted);
}

.breadcrumb__item a:hover {
  color: var(--color-primary);
}

.breadcrumb__item[aria-current="page"] {
  color: var(--color-dark);
  font-weight: 600;
}

/* Hero */
.article-hero {
  max-width: var(--max-wide);
  margin: 0 auto;
  padding: 28px 24px 40px;
}

.article-hero__card {
  background: linear-gradient(135deg, var(--color-dark) 0%, var(--color-dark-soft) 100%);
  border-radius: var(--radius-xl);
  padding: 40px 36px;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.article-hero__card::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 280px;
  height: 280px;
  background: radial-gradient(circle, rgba(185, 28, 28, 0.35) 0%, transparent 70%);
  pointer-events: none;
}

.article-hero__card::after {
  content: "";
  position: absolute;
  bottom: -40px;
  left: -40px;
  width: 200px;
  height: 200px;
  background: radial-gradient(circle, rgba(250, 204, 21, 0.12) 0%, transparent 70%);
  pointer-events: none;
}

.article-hero__category {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(250, 204, 21, 0.15);
  color: var(--color-gold);
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 18px;
  position: relative;
}

.article-hero__title {
  font-size: clamp(1.75rem, 4.5vw, 2.625rem);
  font-weight: 800;
  line-height: 1.22;
  color: #fff;
  letter-spacing: -0.02em;
  margin-bottom: 18px;
  position: relative;
  max-width: 720px;
}

.article-hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px 22px;
  color: rgba(255, 255, 255, 0.72);
  font-size: 0.8125rem;
  margin-bottom: 22px;
  position: relative;
}

.article-hero__meta-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.article-hero__excerpt {
  font-size: 1.0625rem;
  color: rgba(255, 255, 255, 0.85);
  line-height: 1.7;
  max-width: 680px;
  position: relative;
  border-left: 3px solid var(--color-gold);
  padding-left: 18px;
}

/* Layout with sticky TOC */
.article-layout {
  max-width: var(--max-wide);
  margin: 0 auto;
  padding: 0 24px 64px;
  display: grid;
  grid-template-columns: var(--toc-width) 1fr;
  gap: 40px;
  align-items: start;
}

/* TOC sticky */
.toc-sidebar {
  position: sticky;
  top: calc(var(--header-h) + 24px);
}

.toc-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-md);
}

.toc-card__title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-primary);
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-gold);
}

.toc-card__list {
  list-style: none;
}

.toc-card__list li {
  margin-bottom: 4px;
}

.toc-card__list a {
  display: block;
  font-size: 0.8125rem;
  color: var(--color-text-muted);
  padding: 7px 10px;
  border-radius: var(--radius-sm);
  border-left: 2px solid transparent;
  transition: all var(--transition);
  line-height: 1.45;
}

.toc-card__list a:hover,
.toc-card__list a.active {
  color: var(--color-primary);
  background: rgba(185, 28, 28, 0.05);
  border-left-color: var(--color-primary);
}

/* Article content */
.article-body {
  min-width: 0;
  max-width: var(--max-content);
}

.article-content h2 {
  font-size: clamp(1.3rem, 2.5vw, 1.625rem);
  font-weight: 700;
  color: var(--color-dark);
  margin: 44px 0 18px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-border);
  scroll-margin-top: calc(var(--header-h) + 20px);
}

.article-content h2:first-child {
  margin-top: 0;
}

.article-content h3 {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-dark-soft);
  margin: 28px 0 12px;
  scroll-margin-top: calc(var(--header-h) + 20px);
}

.article-content p {
  margin-bottom: 18px;
  color: var(--color-text);
}

.article-content strong {
  color: var(--color-dark);
  font-weight: 600;
}

.article-content ul,
.article-content ol {
  margin: 0 0 20px 22px;
  color: var(--color-text);
}

.article-content li {
  margin-bottom: 8px;
}

.article-content li::marker {
  color: var(--color-primary);
}

/* Info boxes */
.info-box {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 22px 26px;
  margin: 24px 0;
  box-shadow: var(--shadow-card);
}

.info-box--key {
  border-left: 4px solid var(--color-primary);
}

.info-box--tip {
  border-left: 4px solid var(--color-gold);
  background: linear-gradient(135deg, #fffbeb 0%, #fff 100%);
}

.info-box--note {
  border-left: 4px solid var(--color-secondary);
}

.info-box__label {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  margin-bottom: 8px;
  display: block;
}

.info-box--key .info-box__label { color: var(--color-primary); }
.info-box--tip .info-box__label { color: var(--color-gold-dark); }
.info-box--note .info-box__label { color: var(--color-secondary); }

.info-box p:last-child {
  margin-bottom: 0;
}

/* Table */
.data-table {
  width: 100%;
  border-collapse: collapse;
  margin: 24px 0;
  font-size: 0.875rem;
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.data-table caption {
  text-align: left;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--color-dark);
  caption-side: top;
}

.data-table th,
.data-table td {
  padding: 13px 16px;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.data-table th {
  background: var(--color-dark);
  color: #fff;
  font-weight: 600;
  font-size: 0.8125rem;
}

.data-table td {
  background: var(--color-bg-card);
  color: var(--color-text);
}

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

.data-table tbody tr:hover td {
  background: rgba(185, 28, 28, 0.03);
}

/* Internal link card */
.link-card {
  display: block;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin: 24px 0;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}

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

.link-card__tag {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-primary);
  margin-bottom: 6px;
}

.link-card__title {
  font-weight: 600;
  color: var(--color-dark);
  font-size: 1rem;
}

.link-card__desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-top: 4px;
}

/* Author box */
.author-box {
  margin: 48px 0 40px;
}

.author-box__inner {
  display: flex;
  gap: 22px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px;
  box-shadow: var(--shadow-md);
}

.author-box__avatar {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  font-weight: 800;
  color: #fff;
  flex-shrink: 0;
  border: 3px solid var(--color-gold);
}

.author-box__label {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-light);
  margin-bottom: 4px;
}

.author-box__name {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--color-dark);
  margin-bottom: 4px;
}

.author-box__role {
  font-size: 0.8125rem;
  color: var(--color-primary);
  font-weight: 600;
  margin-bottom: 10px;
}

.author-box__bio {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  line-height: 1.65;
}

/* FAQ */
.faq-section {
  margin: 48px 0;
  padding-top: 40px;
  border-top: 2px solid var(--color-border);
}

.faq-section__title {
  font-size: clamp(1.375rem, 2.5vw, 1.625rem);
  font-weight: 700;
  color: var(--color-dark);
  margin-bottom: 8px;
}

.faq-section__subtitle {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  margin-bottom: 24px;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.faq-item {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.faq-item:hover {
  border-color: rgba(185, 28, 28, 0.25);
}

.faq-item[open] {
  box-shadow: var(--shadow-sm);
  border-color: rgba(185, 28, 28, 0.3);
}

.faq-item__question {
  width: 100%;
  background: none;
  border: none;
  color: var(--color-dark);
  font-family: inherit;
  font-size: 0.9375rem;
  font-weight: 600;
  text-align: left;
  padding: 18px 22px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  list-style: none;
}

.faq-item__question::-webkit-details-marker {
  display: none;
}

.faq-item__question::after {
  content: "+";
  font-size: 1.25rem;
  color: var(--color-primary);
  flex-shrink: 0;
  transition: transform var(--transition);
  font-weight: 400;
}

.faq-item[open] .faq-item__question::after {
  transform: rotate(45deg);
}

.faq-item__answer {
  padding: 0 22px 18px;
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
}

.faq-item__answer p:last-child {
  margin-bottom: 0;
}

/* Related articles */
.related-section {
  margin: 48px 0;
  padding-top: 40px;
  border-top: 2px solid var(--color-border);
}

.related-section__title {
  font-size: clamp(1.375rem, 2.5vw, 1.625rem);
  font-weight: 700;
  color: var(--color-dark);
  margin-bottom: 8px;
}

.related-section__subtitle {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  margin-bottom: 24px;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 18px;
}

.related-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 22px;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  box-shadow: var(--shadow-sm);
}

.related-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(185, 28, 28, 0.2);
}

.related-card__tag {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-gold-dark);
  margin-bottom: 8px;
}

.related-card__title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-dark);
  margin-bottom: 8px;
  line-height: 1.4;
}

.related-card__title a {
  color: inherit;
}

.related-card__title a:hover {
  color: var(--color-primary);
}

.related-card__excerpt {
  font-size: 0.8125rem;
  color: var(--color-text-muted);
  flex-grow: 1;
  margin-bottom: 14px;
  line-height: 1.6;
}

.related-card__link {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-primary);
}

/* CTA */
.cta-section {
  margin: 48px 0 0;
}

.cta-box {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 50%, var(--color-dark) 100%);
  border-radius: var(--radius-xl);
  padding: 44px 36px;
  text-align: center;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.cta-box::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 80% 20%, rgba(250, 204, 21, 0.15), transparent 50%);
  pointer-events: none;
}

.cta-box__title {
  font-size: clamp(1.375rem, 3vw, 1.75rem);
  font-weight: 800;
  color: #fff;
  margin-bottom: 12px;
  position: relative;
}

.cta-box__text {
  color: rgba(255, 255, 255, 0.88);
  max-width: 520px;
  margin: 0 auto 26px;
  font-size: 1rem;
  position: relative;
  line-height: 1.65;
}

.cta-box__button {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--color-gold);
  color: var(--color-dark);
  font-weight: 700;
  font-size: 0.9375rem;
  padding: 14px 32px;
  border-radius: 999px;
  transition: transform var(--transition), box-shadow var(--transition);
  position: relative;
}

.cta-box__button:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.25);
  color: var(--color-dark);
}

/* Footer */
.site-footer {
  background: var(--color-dark);
  color: rgba(255, 255, 255, 0.6);
  padding: 32px 24px;
  text-align: center;
  font-size: 0.8125rem;
  margin-top: 64px;
}

.site-footer a {
  color: rgba(255, 255, 255, 0.8);
}

.site-footer a:hover {
  color: var(--color-gold);
}

.site-footer__brand {
  font-weight: 700;
  color: #fff;
  margin-bottom: 8px;
}

/* Responsive */
@media (max-width: 1024px) {
  .article-layout {
    grid-template-columns: 1fr;
  }

  .toc-sidebar {
    position: static;
    order: -1;
  }

  .toc-card__list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 4px;
  }
}

@media (max-width: 768px) {
  .site-nav {
    display: none;
  }

  .article-hero__card {
    padding: 28px 22px;
  }

  .author-box__inner {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .toc-card__list {
    grid-template-columns: 1fr;
  }

  .data-table {
    display: block;
    overflow-x: auto;
  }

  .cta-box {
    padding: 32px 22px;
  }
}

@media (max-width: 480px) {
  .article-layout {
    padding: 0 16px 48px;
  }

  .breadcrumb-wrap,
  .article-hero {
    padding-left: 16px;
    padding-right: 16px;
  }
}

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

@media print {
  .site-header, .toc-sidebar, .cta-section, .site-footer, .skip-link {
    display: none;
  }
  body { background: #fff; }
  .article-hero__card {
    background: none;
    color: #000;
    padding: 0;
    box-shadow: none;
  }
  .article-hero__title,
  .article-hero__excerpt { color: #000; }
}