/* ============================================================
   Design tokens
   ============================================================ */
:root {
  --c-primary: #0e7c8a;
  --c-primary-dark: #075763;
  --c-primary-light: #2aa6b5;
  --c-accent: #f59e0b;
  --c-accent-soft: #fef3c7;
  --c-success: #10b981;
  --c-danger: #dc2626;
  --c-info: #2563eb;

  --c-bg: #f5fafb;
  --c-surface: #ffffff;
  --c-surface-elev: #ffffff;
  --c-surface-tint: #eef7f9;
  --c-border: #d8e6e9;
  --c-border-soft: #e8f0f2;

  --c-text: #0f1e22;
  --c-text-muted: #4a6066;
  --c-text-subtle: #6b8086;

  --c-code-bg: #f4f8fa;
  --c-code-border: #dde9ec;
  --c-inline-bg: #eaf3f5;
  --c-inline-text: #075763;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --shadow-sm: 0 1px 2px rgba(15, 30, 34, 0.04), 0 1px 3px rgba(15, 30, 34, 0.06);
  --shadow-md: 0 4px 12px rgba(15, 30, 34, 0.06), 0 2px 4px rgba(15, 30, 34, 0.04);
  --shadow-lg: 0 18px 40px -12px rgba(7, 87, 99, 0.18), 0 8px 16px rgba(15, 30, 34, 0.05);

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --space-8: 4rem;
  --space-9: 6rem;

  --header-h: 64px;

  --max-w: 1400px;
  --max-w-prose: 1100px;

  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "JetBrains Mono", "Fira Code", Menlo, Consolas, monospace;
}

/* ============================================================
   Base
   ============================================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1rem);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-text);
  font-family: var(--font-sans);
  font-size: clamp(15px, 0.95rem + 0.1vw, 17px);
  line-height: 1.65;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
}

main {
  flex: 1 0 auto;
}

img,
svg {
  max-width: 100%;
  height: auto;
}

a {
  color: var(--c-primary);
  text-decoration-color: rgba(14, 124, 138, 0.35);
  text-underline-offset: 3px;
  transition: color 0.15s ease, text-decoration-color 0.15s ease, background-color 0.15s ease;
}

a:hover,
a:focus-visible {
  color: var(--c-primary-dark);
  text-decoration-color: var(--c-primary-dark);
}

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

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--c-primary);
  color: #fff;
  padding: 0.75rem 1rem;
  z-index: 1000;
  border-radius: 0 0 var(--radius-md) 0;
}

.skip-link:focus {
  left: 0;
}

/* ============================================================
   Layout containers
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 clamp(1rem, 3vw, 2rem);
}

.container-prose {
  width: 100%;
  max-width: var(--max-w-prose);
  margin: 0 auto;
  padding: 0 clamp(1rem, 3vw, 2rem);
}

/* ============================================================
   Header
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(160%) blur(10px);
  -webkit-backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--c-border-soft);
  height: var(--header-h);
  display: flex;
  align-items: center;
}

.site-header .container {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  width: 100%;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 700;
  color: var(--c-primary-dark);
  text-decoration: none;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
}

.brand:hover {
  color: var(--c-primary);
}

.brand-logo {
  width: 36px;
  height: 36px;
  flex: none;
}

.brand-name {
  white-space: nowrap;
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-left: auto;
}

.nav a {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-md);
  text-decoration: none;
  color: var(--c-text-muted);
  font-weight: 500;
  font-size: 0.94rem;
  transition: background 0.15s ease, color 0.15s ease;
}

.nav a:hover,
.nav a:focus-visible {
  background: var(--c-surface-tint);
  color: var(--c-primary-dark);
}

.nav a[aria-current="page"] {
  background: var(--c-primary);
  color: #fff;
}

.nav a svg {
  width: 16px;
  height: 16px;
}

.nav-toggle {
  display: none;
  margin-left: auto;
  background: none;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: 0.4rem 0.6rem;
  cursor: pointer;
  color: var(--c-text);
}

@media (max-width: 760px) {
  .brand-name {
    display: none;
  }
  .nav-toggle {
    display: inline-flex;
    align-items: center;
  }
  .nav {
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    margin: 0;
    flex-direction: column;
    background: var(--c-surface);
    border-bottom: 1px solid var(--c-border-soft);
    padding: 0.5rem;
    gap: 0.25rem;
    box-shadow: var(--shadow-md);
    display: none;
  }
  .nav.open {
    display: flex;
  }
  .nav a {
    width: 100%;
  }
}

/* ============================================================
   Hero (homepage)
   ============================================================ */
.hero {
  padding: clamp(2.5rem, 6vw, 5rem) 0 clamp(2rem, 5vw, 4rem);
  background:
    radial-gradient(circle at 12% 8%, rgba(42, 166, 181, 0.18), transparent 55%),
    radial-gradient(circle at 92% 12%, rgba(245, 158, 11, 0.14), transparent 55%),
    linear-gradient(180deg, var(--c-bg) 0%, var(--c-surface) 100%);
  border-bottom: 1px solid var(--c-border-soft);
}

.hero-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: var(--space-5);
}

.hero-logo {
  width: clamp(140px, 22vw, 220px);
  height: auto;
  filter: drop-shadow(0 12px 24px rgba(14, 124, 138, 0.18));
}

.hero h1 {
  margin: 0;
  font-size: clamp(2rem, 2vw + 1.4rem, 3.25rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  background: linear-gradient(120deg, var(--c-primary-dark), var(--c-primary-light) 65%, var(--c-accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  max-width: 22ch;
}

.hero-tagline {
  max-width: 56ch;
  color: var(--c-text-muted);
  font-size: clamp(1.05rem, 0.4vw + 1rem, 1.2rem);
  margin: 0;
}

.hero-intro {
  max-width: 70ch;
  color: var(--c-text);
  margin: var(--space-4) 0 0;
}

.cta-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-4);
  width: 100%;
  margin-top: var(--space-5);
}

.cta {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.9rem 1.1rem;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  color: var(--c-text);
  text-decoration: none;
  font-weight: 600;
  box-shadow: var(--shadow-sm);
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}

.cta:hover,
.cta:focus-visible {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  border-color: var(--c-primary-light);
  color: var(--c-primary-dark);
}

.cta-icon {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
  background: var(--c-surface-tint);
}

.cta-icon svg {
  width: 22px;
  height: 22px;
}

.cta-icon.icon-architecture {
  background: linear-gradient(135deg, #cffafe, #a5f3fc);
  color: #075763;
}
.cta-icon.icon-iot {
  background: linear-gradient(135deg, #ddd6fe, #c7d2fe);
  color: #4338ca;
}
.cta-icon.icon-excursion {
  background: linear-gradient(135deg, #fed7aa, #fecaca);
  color: #b91c1c;
}

/* ============================================================
   Section cards on homepage
   ============================================================ */
.sections-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-5);
  padding: clamp(2rem, 5vw, 4rem) 0;
}

.section-card {
  background: var(--c-surface);
  border: 1px solid var(--c-border-soft);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.section-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: var(--c-primary-light);
}

.section-card h2 {
  margin: 0;
  font-size: 1.25rem;
  color: var(--c-primary-dark);
}

.section-card h2 a {
  color: inherit;
  text-decoration: none;
}

.section-card h2 a:hover {
  color: var(--c-primary);
}

.section-card p {
  margin: 0;
  color: var(--c-text-muted);
  font-size: 0.96rem;
}

.section-card ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.section-card ul a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--c-text);
  padding: 0.35rem 0.5rem;
  margin: 0 -0.5rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
}

.section-card ul a::before {
  content: "→";
  color: var(--c-primary);
  font-weight: 700;
}

.section-card ul a:hover {
  background: var(--c-surface-tint);
  color: var(--c-primary-dark);
}

.home-intro {
  background: var(--c-surface);
  border-top: 1px solid var(--c-border-soft);
  border-bottom: 1px solid var(--c-border-soft);
  padding: clamp(2rem, 5vw, 3.5rem) 0;
}

.home-intro h2 {
  margin: 0 0 var(--space-3);
  color: var(--c-primary-dark);
  font-size: clamp(1.4rem, 0.6vw + 1.2rem, 1.85rem);
}

.home-intro p {
  max-width: 75ch;
  margin: 0 0 var(--space-3);
  color: var(--c-text);
}

/* ============================================================
   Content (article)
   ============================================================ */
.content {
  padding: clamp(1.5rem, 3vw, 2.5rem) 0 clamp(2rem, 5vw, 4rem);
}

.content-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6);
}

@media (min-width: 1100px) {
  .content-layout {
    grid-template-columns: minmax(0, 1fr) 300px;
  }
}

.content-aside {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

@media (min-width: 1100px) {
  .content-aside {
    position: sticky;
    top: calc(var(--header-h) + var(--space-4));
    align-self: start;
    max-height: calc(100vh - var(--header-h) - 2rem);
    overflow-y: auto;
    padding-right: 4px;
  }
}

.page-meta {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.82rem;
  color: var(--c-text-subtle);
  padding: 0.5rem 0.75rem;
  background: var(--c-surface);
  border: 1px solid var(--c-border-soft);
  border-radius: var(--radius-md);
}

.page-meta::before {
  content: "";
  width: 14px;
  height: 14px;
  flex: none;
  background-color: currentColor;
  -webkit-mask: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2.2' stroke-linecap='round' stroke-linejoin='round'><circle cx='12' cy='12' r='10'/><polyline points='12 6 12 12 16 14'/></svg>") center/contain no-repeat;
          mask: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2.2' stroke-linecap='round' stroke-linejoin='round'><circle cx='12' cy='12' r='10'/><polyline points='12 6 12 12 16 14'/></svg>") center/contain no-repeat;
}

.toc {
  background: var(--c-surface);
  border: 1px solid var(--c-border-soft);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-5);
}

.toc-title {
  margin: 0 0 var(--space-3);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--c-text-subtle);
  border-bottom: 2px solid var(--c-primary-light);
  padding-bottom: 0.5rem;
}

.toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: toc;
}

.toc-list li {
  margin: 0;
  display: block;
}

.toc-list a {
  display: block;
  padding: 0.35rem 0.55rem 0.35rem 0.6rem;
  margin: 0 -0.55rem;
  border-radius: var(--radius-sm);
  color: var(--c-text);
  text-decoration: none;
  font-size: 0.88rem;
  line-height: 1.4;
  border-left: 3px solid transparent;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.toc-list a:hover,
.toc-list a:focus-visible {
  background: var(--c-surface-tint);
  color: var(--c-primary-dark);
}

.toc-list a.is-active {
  background: var(--c-surface-tint);
  color: var(--c-primary-dark);
  border-left-color: var(--c-primary);
  font-weight: 600;
}

.toc-list .toc-level-3 a {
  padding-left: 1.3rem;
  font-size: 0.84rem;
  color: var(--c-text-muted);
}

article.prose {
  max-width: none;
}

article.prose h1 {
  margin: 0 0 var(--space-4);
  font-size: clamp(1.85rem, 1.3vw + 1.4rem, 2.6rem);
  letter-spacing: -0.02em;
  line-height: 1.15;
  background: linear-gradient(120deg, var(--c-primary-dark), var(--c-primary-light) 80%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

article.prose h2 {
  margin-top: var(--space-7);
  margin-bottom: var(--space-3);
  color: var(--c-primary-dark);
  font-size: clamp(1.35rem, 0.6vw + 1.15rem, 1.7rem);
  letter-spacing: -0.01em;
  border-bottom: 2px solid var(--c-surface-tint);
  padding-bottom: 0.4rem;
}

article.prose h3 {
  margin-top: var(--space-6);
  margin-bottom: var(--space-3);
  color: var(--c-primary-dark);
  font-size: 1.2rem;
}

article.prose h4 {
  margin-top: var(--space-5);
  margin-bottom: var(--space-2);
  color: var(--c-text);
  font-size: 1.05rem;
}

article.prose p {
  margin: 0 0 var(--space-4);
  color: var(--c-text);
}

article.prose ul,
article.prose ol {
  margin: 0 0 var(--space-4);
  padding-left: 1.4rem;
}

article.prose li {
  margin-bottom: 0.4rem;
}

article.prose strong {
  color: var(--c-primary-dark);
}

article.prose blockquote {
  margin: 0 0 var(--space-4);
  padding: 0.8rem 1.1rem;
  border-left: 4px solid var(--c-primary-light);
  background: var(--c-surface-tint);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  color: var(--c-text-muted);
}

.heading-link {
  color: inherit;
  text-decoration: none;
}

.heading-link:hover {
  color: var(--c-primary);
}

/* Inline code */
article.prose :not(pre) > code {
  background: var(--c-inline-bg);
  color: var(--c-inline-text);
  padding: 0.1em 0.4em;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.9em;
  border: 0;
}

/* Code blocks */
.code-block {
  position: relative;
  margin: 0 0 var(--space-5);
  border-radius: var(--radius-md);
  background: var(--c-code-bg);
  border: 1px solid var(--c-code-border);
  overflow: hidden;
}

.code-block pre {
  margin: 0;
  padding: 1.1rem 1rem;
  background: transparent !important;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.55;
  overflow-x: auto;
  color: #1d2c30;
  tab-size: 2;
}

.code-block code {
  font-family: inherit;
  font-size: inherit;
  background: transparent;
  padding: 0;
  border: 0;
}

.code-lang {
  position: absolute;
  top: 0.45rem;
  left: 0.7rem;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--c-text-subtle);
  background: rgba(255, 255, 255, 0.7);
  padding: 0.15rem 0.45rem;
  border-radius: 4px;
  pointer-events: none;
}

.code-block pre[class*="language-"] {
  padding-top: 1.85rem;
}

.copy-btn {
  position: absolute;
  top: 0.4rem;
  right: 0.5rem;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  background: rgba(255, 255, 255, 0.85);
  border: 1px solid var(--c-border);
  color: var(--c-text-muted);
  font: inherit;
  font-size: 0.78rem;
  padding: 0.25rem 0.55rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
  z-index: 2;
}

.copy-btn:hover,
.copy-btn:focus-visible {
  background: var(--c-primary);
  color: #fff;
  border-color: var(--c-primary);
}

.copy-btn.copied {
  background: var(--c-success);
  color: #fff;
  border-color: var(--c-success);
}

/* Tables */
.table-wrap {
  overflow-x: auto;
  margin: 0 0 var(--space-5);
  border: 1px solid var(--c-border-soft);
  border-radius: var(--radius-md);
  background: var(--c-surface);
}

.table-wrap table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.94rem;
}

.table-wrap th,
.table-wrap td {
  text-align: left;
  padding: 0.65rem 0.9rem;
  border-bottom: 1px solid var(--c-border-soft);
  vertical-align: top;
}

.table-wrap thead th {
  background: var(--c-surface-tint);
  color: var(--c-primary-dark);
  font-weight: 600;
  border-bottom: 2px solid var(--c-primary-light);
}

.table-wrap tbody tr:hover {
  background: var(--c-surface-tint);
}

/* Task lists */
.task-list-item {
  list-style: none;
  margin-left: -1.4rem;
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
}

.task-list-item input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 1.1em;
  height: 1.1em;
  margin-top: 0.3em;
  border: 1.5px solid var(--c-primary);
  border-radius: 4px;
  background: var(--c-surface);
  cursor: pointer;
  display: inline-grid;
  place-content: center;
  flex: none;
  transition: background 0.15s, border-color 0.15s;
}

.task-list-item input[type="checkbox"]:checked {
  background: var(--c-primary);
  border-color: var(--c-primary);
}

.task-list-item input[type="checkbox"]:checked::after {
  content: "";
  width: 0.55em;
  height: 0.3em;
  border-left: 2px solid #fff;
  border-bottom: 2px solid #fff;
  transform: rotate(-45deg) translateY(-0.1em);
}

.task-list-item.is-checked,
.task-list-item input[type="checkbox"]:checked ~ * {
  text-decoration: line-through;
  color: var(--c-text-subtle);
}

ul:has(> .task-list-item) {
  padding-left: 1.4rem;
}

/* Mermaid */
.mermaid {
  margin: 0 0 var(--space-5);
  padding: 1rem;
  background: var(--c-surface);
  border: 1px solid var(--c-border-soft);
  border-radius: var(--radius-md);
  overflow-x: auto;
  text-align: center;
}

/* KaTeX adjustments */
.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.25rem 0;
}

/* ============================================================
   Breadcrumbs
   ============================================================ */
.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.5rem;
  list-style: none;
  margin: 0 0 var(--space-4);
  padding: 0;
  font-size: 0.88rem;
  color: var(--c-text-subtle);
}

.breadcrumbs li {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.breadcrumbs li + li::before {
  content: "›";
  color: var(--c-text-subtle);
}

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

.breadcrumbs a:hover {
  color: var(--c-primary-dark);
  text-decoration: underline;
}

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

/* ============================================================
   Related links sidebar / footer
   ============================================================ */
.related {
  background: var(--c-surface);
  border: 1px solid var(--c-border-soft);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.related h2 {
  margin: 0;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--c-text-subtle);
}

.related ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.related a {
  display: block;
  padding: 0.45rem 0.55rem;
  margin: 0 -0.55rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: var(--c-text);
  font-size: 0.92rem;
  line-height: 1.4;
  transition: background 0.15s, color 0.15s;
}

.related a:hover {
  background: var(--c-surface-tint);
  color: var(--c-primary-dark);
}

.related a[aria-current="page"] {
  background: var(--c-surface-tint);
  color: var(--c-primary-dark);
  font-weight: 600;
}


/* ============================================================
   Accordion (FAQ)
   ============================================================ */
details.faq-item {
  background: var(--c-surface);
  border: 1px solid var(--c-border-soft);
  border-radius: var(--radius-md);
  padding: 0;
  margin: 0 0 var(--space-3);
  overflow: hidden;
}

details.faq-item[open] {
  border-color: var(--c-primary-light);
  box-shadow: var(--shadow-sm);
}

details.faq-item > summary {
  cursor: pointer;
  list-style: none;
  padding: 0.9rem 1.1rem;
  font-weight: 600;
  color: var(--c-primary-dark);
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  background: var(--c-surface);
  transition: background 0.15s;
}

details.faq-item > summary::-webkit-details-marker {
  display: none;
}

details.faq-item > summary::after {
  content: "+";
  margin-left: auto;
  font-size: 1.4rem;
  line-height: 1;
  color: var(--c-primary);
  transition: transform 0.18s;
}

details.faq-item[open] > summary::after {
  content: "−";
}

details.faq-item > summary:hover {
  background: var(--c-surface-tint);
}

details.faq-item > .faq-body {
  padding: 0 1.1rem 1rem;
  border-top: 1px solid var(--c-border-soft);
}

details.faq-item > .faq-body > *:first-child {
  margin-top: 1rem;
}

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  flex-shrink: 0;
  background:
    linear-gradient(180deg, var(--c-surface) 0%, var(--c-surface-tint) 100%);
  border-top: 1px solid var(--c-border-soft);
  padding: var(--space-7) 0 var(--space-5);
  margin-top: var(--space-7);
  color: var(--c-text-muted);
  font-size: 0.92rem;
}

.site-footer .container {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
  align-items: start;
}

@media (min-width: 720px) {
  .site-footer .container {
    grid-template-columns: 1.4fr 1fr 1fr 1fr;
    gap: var(--space-5);
  }
}

.footer-col {
  min-width: 0;
}

.footer-col h3 {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  margin: 0 0 var(--space-3);
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--c-primary-light);
  color: var(--c-primary-dark);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.footer-col h3 svg {
  width: 16px;
  height: 16px;
  color: var(--c-primary);
  flex: none;
}

.footer-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.footer-links li {
  margin: 0;
}

.footer-link {
  position: relative;
  display: block;
  padding: 0.4rem 0.55rem 0.4rem 1.1rem;
  margin: 0 -0.55rem;
  border-radius: var(--radius-sm);
  color: var(--c-text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  line-height: 1.35;
  transition: background 0.15s, color 0.15s, padding 0.15s;
}

.footer-link::before {
  content: "";
  position: absolute;
  left: 0.55rem;
  top: 50%;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--c-primary-light);
  transform: translateY(-50%);
  opacity: 0.55;
  transition: opacity 0.15s, width 0.15s, background 0.15s;
}

.footer-link:hover,
.footer-link:focus-visible {
  background: rgba(255, 255, 255, 0.6);
  color: var(--c-primary-dark);
  padding-left: 1.2rem;
}

.footer-link:hover::before,
.footer-link:focus-visible::before {
  background: var(--c-accent);
  opacity: 1;
  width: 6px;
}

.footer-link-overview {
  font-weight: 600;
  color: var(--c-primary-dark);
}

.footer-link-overview::before {
  background: var(--c-primary);
  opacity: 1;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  max-width: 34ch;
}

.footer-brand .brand {
  font-size: 1rem;
}

.footer-brand p {
  margin: 0;
  color: var(--c-text-muted);
  line-height: 1.55;
}

.site-footer .container:last-child {
  display: block;
  margin-top: 0;
}

.footer-bottom {
  border-top: 1px solid var(--c-border-soft);
  margin-top: var(--space-5);
  padding-top: var(--space-3);
  font-size: 0.82rem;
  color: var(--c-text-subtle);
  text-align: center;
}

/* ============================================================
   Section header (top of section pages)
   ============================================================ */
.section-hero {
  padding: clamp(1.5rem, 3vw, 2.5rem) 0;
  border-bottom: 1px solid var(--c-border-soft);
  background:
    radial-gradient(circle at 90% 0%, rgba(42, 166, 181, 0.1), transparent 50%),
    var(--c-surface);
}

/* ============================================================
   Print
   ============================================================ */
@media print {
  .site-header,
  .site-footer,
  .related,
  .copy-btn,
  .cta-row {
    display: none !important;
  }
  body {
    background: #fff;
  }
}