/* ==========================================================================
   TelecomExplained.com — Global Editorial Design System
   Aesthetic: Authority Reference Publication & Technical Telecom Knowledge Base
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:ital,opsz,wght@0,14..32,100..900;1,14..32,100..900&family=JetBrains+Mono:wght@400;500;600&family=Newsreader:ital,opsz,wght@0,6..72,300..800;1,6..72,300..800&display=swap');

/* --- Design Tokens & CSS Custom Properties --- */
:root {
  /* Editorial Color Palette */
  --color-ink-primary: #0f172a;       /* Deep slate ink for headlines */
  --color-ink-body: #334155;          /* Crisp neutral for long-form reading */
  --color-ink-muted: #64748b;         /* Secondary metadata, captions */
  --color-ink-faint: #94a3b8;         /* Subtle borders, timestamps */
  --color-ink-inverse: #ffffff;

  /* Surfaces & Canvas */
  --color-canvas-base: #fcfcfb;       /* Warm editorial paper/canvas */
  --color-canvas-subtle: #f4f5f6;     /* Tinted neutral section backgrounds */
  --color-canvas-card: #ffffff;       /* Pure white card surface */
  --color-canvas-dark: #0a111a;       /* Dark footer & masthead accents */
  --color-canvas-dark-surface: #131e2b;

  /* Brand Accent: Spruce / Editorial Deep Teal */
  --color-accent: #0f515c;            /* Subdued, authoritative teal-spruce */
  --color-accent-hover: #0a3a42;
  --color-accent-light: #eef6f7;
  --color-accent-border: #c8e1e5;

  /* Subtle Warm Highlights */
  --color-warm-tag: #f7efe6;
  --color-warm-text: #8c531b;
  --color-warm-border: #eddccb;

  /* Status / Notice Tones */
  --color-notice-bg: #fbf8f1;
  --color-notice-border: #f0e2ca;
  --color-notice-text: #784c17;
  
  --color-info-bg: #f0f7fa;
  --color-info-border: #d4e8f0;
  --color-info-text: #1b536b;

  /* Lines & Borders */
  --color-border: #e3e6ea;
  --color-border-subtle: #edf0f2;
  --color-border-heavy: #cbd5e1;

  /* Typography Stacks */
  --font-serif: 'Newsreader', Georgia, Cambria, 'Times New Roman', Times, serif;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  /* Type Scale */
  --text-xs: 0.75rem;     /* 12px */
  --text-sm: 0.875rem;    /* 14px */
  --text-base: 1rem;      /* 16px */
  --text-md: 1.125rem;    /* 18px */
  --text-lg: 1.25rem;     /* 20px */
  --text-xl: 1.5rem;      /* 24px */
  --text-2xl: 1.875rem;   /* 30px */
  --text-3xl: 2.25rem;    /* 36px */
  --text-4xl: 2.875rem;   /* 46px */
  --text-5xl: 3.5rem;     /* 56px */

  /* Spacing */
  --space-2xs: 0.25rem;
  --space-xs: 0.5rem;
  --space-sm: 0.75rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4.5rem;
  --space-4xl: 6.5rem;

  /* Layout Containers */
  --container-max: 1180px;
  --container-editorial: 820px;
  --container-narrow: 680px;
  --header-height: 72px;

  /* Radius & Shadows */
  --radius-xs: 3px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-pill: 9999px;

  --shadow-subtle: 0 1px 3px rgba(15, 23, 42, 0.04), 0 1px 2px rgba(15, 23, 42, 0.02);
  --shadow-card: 0 4px 12px -2px rgba(15, 23, 42, 0.05), 0 2px 6px -1px rgba(15, 23, 42, 0.03);
  --shadow-elevated: 0 12px 28px -4px rgba(15, 23, 42, 0.08), 0 4px 10px -2px rgba(15, 23, 42, 0.04);

  /* Transitions */
  --transition-fast: 140ms ease;
  --transition-base: 220ms ease;
  --transition-drawer: 320ms cubic-bezier(0.16, 1, 0.3, 1);
}

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

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

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.68;
  color: var(--color-ink-body);
  background-color: var(--color-canvas-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  overflow-x: hidden;
}

/* Accessibility: Focus Styles */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

.skip-to-content {
  position: absolute;
  top: -100px;
  left: 1.5rem;
  background: var(--color-ink-primary);
  color: #fff;
  padding: 0.75rem 1.25rem;
  z-index: 9999;
  border-radius: var(--radius-sm);
  font-weight: 500;
  text-decoration: none;
  transition: top var(--transition-fast);
}

.skip-to-content:focus {
  top: 1rem;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  color: var(--color-ink-primary);
  line-height: 1.22;
  font-weight: 600;
  letter-spacing: -0.015em;
  overflow-wrap: break-word;
}

h1 {
  font-size: clamp(2rem, 3.5vw + 0.8rem, var(--text-5xl));
  margin-bottom: var(--space-lg);
  font-weight: 600;
}

h2 {
  font-size: clamp(1.5rem, 2.2vw + 0.5rem, var(--text-3xl));
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
  font-weight: 600;
}

h3 {
  font-size: clamp(1.2rem, 1.4vw + 0.4rem, var(--text-xl));
  margin-top: var(--space-xl);
  margin-bottom: var(--space-sm);
  font-weight: 600;
}

h4 {
  font-family: var(--font-sans);
  font-size: var(--text-md);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-xs);
}

p {
  margin-bottom: var(--space-lg);
  overflow-wrap: break-word;
}

p.lead {
  font-family: var(--font-serif);
  font-size: clamp(1.1rem, 1.2vw + 0.5rem, 1.35rem);
  line-height: 1.55;
  color: var(--color-ink-primary);
  margin-bottom: var(--space-xl);
  font-weight: 400;
}

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

a:hover {
  color: var(--color-accent-hover);
  text-decoration-thickness: 2px;
}

code, pre {
  font-family: var(--font-mono);
  font-size: 0.9em;
  word-break: break-word;
}

code {
  background: var(--color-canvas-subtle);
  padding: 0.15em 0.35em;
  border-radius: var(--radius-xs);
  border: 1px solid var(--color-border);
  color: var(--color-ink-primary);
}

/* --- Layout Containers --- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-lg);
  padding-right: var(--space-lg);
}

.container-editorial {
  width: 100%;
  max-width: var(--container-editorial);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-lg);
  padding-right: var(--space-lg);
}

.container-narrow {
  width: 100%;
  max-width: var(--container-narrow);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-lg);
  padding-right: var(--space-lg);
}

/* --- Top Masthead & Navigation --- */
.site-header {
  background-color: #ffffff;
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.top-bar-notice {
  background-color: var(--color-canvas-subtle);
  border-bottom: 1px solid var(--color-border-subtle);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  padding: 0.45rem var(--space-lg);
  text-align: center;
  font-family: var(--font-sans);
  letter-spacing: 0.02em;
  line-height: 1.4;
}

.top-bar-notice a {
  color: var(--color-ink-body);
  font-weight: 500;
  text-decoration: underline;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}

.brand-wrapper {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  text-decoration: none;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  min-width: 0;
}

.brand-logo svg {
  flex-shrink: 0;
}

.brand-text {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.brand-title {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-ink-primary);
  letter-spacing: -0.02em;
  line-height: 1.1;
  white-space: nowrap;
}

.brand-tagline {
  font-family: var(--font-sans);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  font-weight: 500;
  white-space: nowrap;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-list {
  display: flex;
  align-items: center;
  list-style: none;
  gap: 1.75rem;
}

.nav-link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-ink-body);
  text-decoration: none;
  padding: 0.4rem 0;
  position: relative;
  transition: color var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-accent);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--color-accent);
  border-radius: var(--radius-pill);
}

.nav-link-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.nav-link-badge .external-icon {
  width: 12px;
  height: 12px;
  stroke-width: 2.2;
  opacity: 0.7;
}

.mobile-menu-toggle {
  display: none;
  background: none;
  border: 1px solid var(--color-border);
  padding: 0.5rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--color-ink-primary);
  min-height: 40px;
  min-width: 40px;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition-fast), border-color var(--transition-fast);
}

.mobile-menu-toggle:hover {
  background-color: var(--color-canvas-subtle);
  border-color: var(--color-ink-faint);
}

/* ==========================================================================
   Smooth Right-to-Left Off-Canvas Mobile Drawer (70% coverage)
   ========================================================================== */
.mobile-nav-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(11, 19, 32, 0.58);
  backdrop-filter: blur(3px);
  -webkit-backdrop-filter: blur(3px);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-drawer), visibility var(--transition-drawer);
  z-index: 1050;
}

.mobile-nav-backdrop.is-open {
  opacity: 1;
  visibility: visible;
}

.mobile-nav-drawer {
  position: fixed;
  top: 0;
  right: 0;
  left: auto;
  bottom: 0;
  width: 70%;
  max-width: 320px;
  min-width: 260px;
  height: 100vh;
  height: 100dvh;
  background: #ffffff;
  z-index: 1100;
  display: flex;
  flex-direction: column;
  box-shadow: -10px 0 35px rgba(15, 23, 42, 0.18);
  transform: translateX(100%);
  visibility: hidden;
  transition: transform var(--transition-drawer), visibility var(--transition-drawer);
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  border-left: 1px solid var(--color-border);
  border-right: none;
}

.mobile-nav-drawer.is-open {
  transform: translateX(0);
  visibility: visible;
}

.mobile-drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.15rem 1.25rem;
  border-bottom: 1px solid var(--color-border);
  background-color: var(--color-canvas-subtle);
}

.mobile-drawer-close {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 0.4rem;
  cursor: pointer;
  color: var(--color-ink-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition-fast);
  min-height: 36px;
  min-width: 36px;
}

.mobile-drawer-close:hover {
  background-color: var(--color-canvas-card);
}

.mobile-drawer-nav {
  padding: 1.25rem;
  flex-grow: 1;
}

.mobile-nav-heading {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  font-weight: 600;
  margin-bottom: 0.65rem;
}

.mobile-nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.mobile-nav-link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-ink-primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.65rem 0.75rem;
  border-radius: var(--radius-sm);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.mobile-nav-link:hover {
  background-color: var(--color-canvas-subtle);
  color: var(--color-accent);
}

.mobile-nav-link.active {
  background-color: var(--color-accent-light);
  color: var(--color-accent);
  font-weight: 600;
}

.mobile-drawer-footer {
  padding: 1.25rem;
  border-top: 1px solid var(--color-border);
  background-color: var(--color-canvas-subtle);
}

.mobile-drawer-disclosure {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  line-height: 1.5;
  margin-bottom: 0.5rem;
}

.mobile-drawer-email {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-accent);
  text-decoration: none;
  font-weight: 500;
  word-break: break-all;
}

/* --- Hero Section --- */
.hero-editorial {
  padding: var(--space-3xl) 0 var(--space-2xl);
  border-bottom: 1px solid var(--color-border);
  background: linear-gradient(180deg, #ffffff 0%, var(--color-canvas-base) 100%);
}

.hero-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: var(--space-md);
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.25rem 0.65rem;
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.03em;
  border-radius: var(--radius-pill);
  text-transform: uppercase;
}

.badge-editorial {
  background-color: var(--color-accent-light);
  color: var(--color-accent);
  border: 1px solid var(--color-accent-border);
}

.badge-disclosure {
  background-color: var(--color-warm-tag);
  color: var(--color-warm-text);
  border: 1px solid var(--color-warm-border);
}

.hero-title {
  margin-bottom: var(--space-md);
  color: var(--color-ink-primary);
}

.hero-lead {
  font-family: var(--font-serif);
  font-size: clamp(1.15rem, 1.3vw + 0.5rem, 1.45rem);
  line-height: 1.55;
  color: #3f4e64;
  max-width: 900px;
  margin-bottom: var(--space-xl);
}

.hero-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

/* Buttons & Action Links */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 500;
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  cursor: pointer;
  min-height: 42px;
  transition: all var(--transition-fast);
}

.btn-primary {
  background-color: var(--color-accent);
  color: #ffffff;
  border: 1px solid var(--color-accent);
}

.btn-primary:hover {
  background-color: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
  color: #ffffff;
}

.btn-secondary {
  background-color: #ffffff;
  color: var(--color-ink-body);
  border: 1px solid var(--color-border-heavy);
}

.btn-secondary:hover {
  background-color: var(--color-canvas-subtle);
  color: var(--color-ink-primary);
  border-color: var(--color-ink-muted);
}

.btn-text {
  background: none;
  border: none;
  color: var(--color-accent);
  padding: 0.5rem 0;
  text-decoration: underline;
  text-underline-offset: 3px;
}

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

/* --- Section Layouts & Components --- */
.section {
  padding: var(--space-3xl) 0;
}

.section-alt {
  background-color: #ffffff;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.section-header {
  margin-bottom: var(--space-2xl);
}

.section-header-centered {
  text-align: center;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
  margin-bottom: var(--space-2xl);
}

.section-subtitle {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-accent);
  font-weight: 600;
  margin-bottom: var(--space-xs);
}

.section-title {
  margin-top: 0;
  margin-bottom: var(--space-sm);
}

.section-description {
  font-size: var(--text-md);
  color: var(--color-ink-muted);
  margin-bottom: 0;
}

/* --- Grid Systems --- */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-xl);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-md);
}

/* --- Reference Topic Cards --- */
.topic-card {
  background: #ffffff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-xl);
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-base), border-color var(--transition-base), box-shadow var(--transition-base);
  position: relative;
}

.topic-card:hover {
  border-color: var(--color-accent-border);
  box-shadow: var(--shadow-card);
  transform: translateY(-2px);
}

.topic-card-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background-color: var(--color-canvas-subtle);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-accent);
  margin-bottom: var(--space-md);
}

.topic-card-title {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  color: var(--color-ink-primary);
  margin-top: 0;
  margin-bottom: var(--space-xs);
}

.topic-card-desc {
  font-size: var(--text-sm);
  color: var(--color-ink-body);
  line-height: 1.6;
  margin-bottom: var(--space-md);
  flex-grow: 1;
}

.topic-card-subtopics {
  list-style: none;
  border-top: 1px solid var(--color-border-subtle);
  padding-top: var(--space-sm);
  margin-bottom: var(--space-md);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.topic-card-subtopics li {
  margin-bottom: 0.35rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.topic-card-subtopics li::before {
  content: '›';
  color: var(--color-accent);
  font-size: 1rem;
  line-height: 1;
}

.topic-card-link {
  font-size: var(--text-sm);
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  text-decoration: none;
  color: var(--color-accent);
}

.topic-card-link:hover {
  color: var(--color-accent-hover);
  text-decoration: underline;
}

/* --- Architectural Protocol Table --- */
.protocol-table-wrapper {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: #ffffff;
  margin-top: var(--space-lg);
  box-shadow: var(--shadow-subtle);
}

.protocol-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: var(--text-sm);
  min-width: 620px;
}

.protocol-table th {
  background-color: var(--color-canvas-subtle);
  color: var(--color-ink-primary);
  font-family: var(--font-sans);
  font-weight: 600;
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--color-border);
  white-space: nowrap;
}

.protocol-table td {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--color-border-subtle);
  vertical-align: top;
}

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

.protocol-table tr:hover td {
  background-color: #fafbfb;
}

.protocol-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  background-color: var(--color-canvas-subtle);
  color: var(--color-accent);
  padding: 0.15rem 0.45rem;
  border-radius: var(--radius-xs);
  border: 1px solid var(--color-border);
}

/* --- Editorial Disclosure & Principle Banners --- */
.disclosure-box {
  background-color: var(--color-notice-bg);
  border: 1px solid var(--color-notice-border);
  border-radius: var(--radius-md);
  padding: var(--space-lg) var(--space-xl);
  margin: var(--space-xl) 0;
  color: var(--color-notice-text);
  font-size: var(--text-sm);
  line-height: 1.65;
  overflow-wrap: break-word;
}

.disclosure-box-title {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: var(--text-base);
  margin-bottom: var(--space-xs);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: #713f12;
}

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

.disclosure-box a {
  color: #713f12;
  font-weight: 600;
  text-decoration: underline;
}

.principles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.principle-item {
  background-color: #ffffff;
  border: 1px solid var(--color-border);
  padding: var(--space-lg);
  border-radius: var(--radius-md);
}

.principle-num {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--space-xs);
}

.principle-title {
  font-family: var(--font-sans);
  font-size: var(--text-md);
  font-weight: 600;
  color: var(--color-ink-primary);
  margin-bottom: var(--space-xs);
}

.principle-desc {
  font-size: var(--text-sm);
  color: var(--color-ink-body);
  margin-bottom: 0;
}

/* --- Accordions (FAQ & Technical Q&A) --- */
.accordion-group {
  margin-top: var(--space-xl);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.accordion-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: #ffffff;
  overflow: hidden;
  transition: border-color var(--transition-fast);
}

.accordion-item:focus-within {
  border-color: var(--color-accent);
}

.accordion-summary {
  padding: 1.15rem 1.25rem;
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-ink-primary);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  background: #ffffff;
  transition: background-color var(--transition-fast);
  gap: 1rem;
}

.accordion-summary::-webkit-details-marker {
  display: none;
}

.accordion-summary:hover {
  background-color: var(--color-canvas-subtle);
}

.accordion-icon {
  width: 18px;
  height: 18px;
  color: var(--color-ink-muted);
  transition: transform var(--transition-fast);
  flex-shrink: 0;
}

details[open] .accordion-icon {
  transform: rotate(180deg);
}

details[open] .accordion-summary {
  border-bottom: 1px solid var(--color-border-subtle);
  background-color: var(--color-canvas-subtle);
}

.accordion-content {
  padding: 1.25rem;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-body);
  background: #ffffff;
}

.accordion-content p:last-child {
  margin-bottom: 0;
}

/* --- Editorial / Document Pages (About, Terms, Privacy, Affiliate, Contact) --- */
.editorial-document {
  padding: var(--space-3xl) 0 var(--space-4xl);
}

.editorial-header {
  border-bottom: 1px solid var(--color-border);
  padding-bottom: var(--space-xl);
  margin-bottom: var(--space-2xl);
}

.doc-metadata {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-sm);
  flex-wrap: wrap;
}

.editorial-body {
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--color-ink-body);
}

.editorial-body h2 {
  font-size: 1.75rem;
  margin-top: var(--space-2xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border-subtle);
}

.editorial-body h3 {
  font-size: 1.3rem;
  margin-top: var(--space-xl);
}

.editorial-body ul, 
.editorial-body ol {
  margin-bottom: var(--space-lg);
  padding-left: 1.5rem;
}

.editorial-body li {
  margin-bottom: 0.5rem;
}

.editorial-body blockquote {
  border-left: 3px solid var(--color-accent);
  padding-left: var(--space-lg);
  margin: var(--space-xl) 0;
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-style: italic;
  color: var(--color-ink-primary);
}

/* --- Site Footer --- */
.site-footer {
  background-color: var(--color-canvas-dark);
  color: #94a3b8;
  border-top: 1px solid #1e293b;
  margin-top: auto;
  padding-top: var(--space-3xl);
  padding-bottom: var(--space-2xl);
  font-size: var(--text-sm);
}

.footer-top {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-3xl);
  padding-bottom: var(--space-2xl);
  border-bottom: 1px solid #1e293b;
}

.footer-brand .brand-title {
  color: #ffffff;
}

.footer-brand .brand-tagline {
  color: #64748b;
}

.footer-desc {
  margin-top: var(--space-md);
  color: #94a3b8;
  font-size: var(--text-sm);
  max-width: 440px;
  line-height: 1.6;
}

.footer-heading {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: #ffffff;
  font-weight: 600;
  margin-bottom: var(--space-md);
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 0.65rem;
}

.footer-links a {
  color: #94a3b8;
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: #ffffff;
  text-decoration: underline;
}

.footer-disclosure-bar {
  padding: var(--space-lg) 0;
  border-bottom: 1px solid #1e293b;
  font-size: var(--text-xs);
  line-height: 1.6;
  color: #cbd5e1;
}

.footer-disclosure-bar a {
  color: #38bdf8;
  text-decoration: underline;
}

.footer-bottom {
  padding-top: var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  font-size: var(--text-xs);
  color: #64748b;
}

.footer-bottom-links {
  display: flex;
  gap: 1.25rem;
  list-style: none;
  flex-wrap: wrap;
}

.footer-bottom-links a {
  color: #64748b;
  text-decoration: none;
}

.footer-bottom-links a:hover {
  color: #cbd5e1;
}

/* --- Breadcrumbs --- */
.breadcrumb-nav {
  margin-bottom: var(--space-lg);
}

.breadcrumb-list {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  list-style: none;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.breadcrumb-item a {
  color: var(--color-ink-muted);
  text-decoration: none;
}

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

.breadcrumb-separator {
  color: var(--color-ink-faint);
}

.breadcrumb-current {
  color: var(--color-ink-primary);
  font-weight: 500;
}

/* --- 404 Layout --- */
.error-page-wrapper {
  padding: var(--space-4xl) 0;
  text-align: center;
  max-width: 640px;
  margin: 0 auto;
}

.error-code {
  font-family: var(--font-serif);
  font-size: clamp(4rem, 10vw, 6rem);
  font-weight: 700;
  line-height: 1;
  color: var(--color-ink-faint);
  margin-bottom: var(--space-xs);
}

/* ==========================================================================
   Responsive Media Queries for All Devices (Mobile, Tablet, Desktop)
   ========================================================================== */

/* Large Tablets & Small Desktops (max-width: 1024px) */
@media (max-width: 1024px) {
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-top {
    grid-template-columns: 1.5fr 1fr 1fr;
    gap: var(--space-xl);
  }
}

/* Tablets & Mobile Devices (max-width: 768px) */
@media (max-width: 768px) {
  :root {
    --header-height: 64px;
    --space-3xl: 2.75rem;
    --space-4xl: 3.5rem;
  }
  
  .container,
  .container-editorial,
  .container-narrow {
    padding-left: 1.25rem;
    padding-right: 1.25rem;
  }

  .site-nav {
    display: none;
  }

  .hero-meta {
    display: none !important;
  }
  
  .mobile-menu-toggle {
    display: flex;
  }
  
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }
  
  .footer-top {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  
  .hero-editorial {
    padding: var(--space-2xl) 0 var(--space-xl);
  }

  .editorial-document {
    padding: var(--space-2xl) 0 var(--space-3xl);
  }

  .editorial-body {
    font-size: 1rem;
  }

  .editorial-body h2 {
    font-size: 1.45rem;
    margin-top: var(--space-xl);
    padding-top: var(--space-md);
  }

  .topic-card {
    padding: var(--space-lg);
  }

  .disclosure-box {
    padding: var(--space-md) var(--space-lg);
  }
}

/* Small Smartphones (max-width: 480px) */
@media (max-width: 480px) {
  :root {
    --header-height: 60px;
    --space-2xl: 2rem;
  }

  .container,
  .container-editorial,
  .container-narrow {
    padding-left: 1rem;
    padding-right: 1rem;
  }

  .top-bar-notice {
    font-size: 0.7rem;
    padding: 0.35rem 0.75rem;
  }

  .brand-title {
    font-size: 1.15rem;
  }

  .brand-tagline {
    font-size: 0.65rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .hero-actions .btn {
    width: 100%;
  }

  .hero-actions .btn-text {
    text-align: center;
  }

  .mobile-nav-drawer {
    width: 70%;
    min-width: 250px;
  }

  .accordion-summary {
    font-size: 1.05rem;
    padding: 1rem;
  }

  .accordion-content {
    padding: 1rem;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
}

/* Print Optimization */
@media print {
  .site-header,
  .site-footer,
  .btn,
  .mobile-menu-toggle,
  .mobile-nav-backdrop,
  .mobile-nav-drawer {
    display: none !important;
  }
  body {
    background: #ffffff;
    color: #000000;
  }
}