/* ==========================================================================
   Edge Notes — Editorial & Developer Workbench Design System
   Pure CSS3 | Zero External Dependencies | Dark Graphite & Accessible Light
   ========================================================================== */

:root,
[data-theme="dark"] {
  --bg-primary: #0b0f17;
  --bg-secondary: #111826;
  --bg-elevated: #161f30;
  --bg-inset: #080b11;
  --bg-hover: #1c273c;

  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --text-faint: #64748b;

  --border-subtle: #1e293b;
  --border-default: #283548;
  --border-strong: #3b4d66;

  --accent-primary: #38bdf8;
  --accent-primary-hover: #7dd3fc;
  --accent-primary-subtle: rgba(56, 189, 248, 0.12);
  --accent-amber: #f59e0b;
  --accent-amber-subtle: rgba(245, 158, 11, 0.14);
  --accent-emerald: #10b981;
  --accent-emerald-subtle: rgba(16, 185, 129, 0.14);
  --accent-rose: #f43f5e;
  --accent-rose-subtle: rgba(244, 63, 94, 0.14);

  --cat-opensource: #38bdf8;
  --cat-dev: #a78bfa;
  --cat-infra: #f59e0b;
  --cat-security: #f43f5e;
  --cat-linux: #10b981;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --code-bg: #080b12;
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-elevated: #f1f5f9;
  --bg-inset: #f1f5f9;
  --bg-hover: #e2e8f0;

  --text-primary: #0f172a;
  --text-secondary: #1e293b;
  --text-muted: #475569;
  --text-faint: #64748b;

  --border-subtle: #e2e8f0;
  --border-default: #cbd5e1;
  --border-strong: #94a3b8;

  --accent-primary: #0284c7;
  --accent-primary-hover: #0369a1;
  --accent-primary-subtle: rgba(2, 132, 199, 0.1);
  --accent-amber: #d97706;
  --accent-amber-subtle: rgba(217, 119, 6, 0.12);
  --accent-emerald: #059669;
  --accent-emerald-subtle: rgba(5, 150, 105, 0.12);
  --accent-rose: #e11d48;
  --accent-rose-subtle: rgba(225, 29, 72, 0.12);

  --cat-opensource: #0284c7;
  --cat-dev: #6d28d9;
  --cat-infra: #b45309;
  --cat-security: #be123c;
  --cat-linux: #047857;

  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.08);
  --code-bg: #f1f5f9;
}

:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --max-width: 1200px;
  --reading-width: 72ch;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
}

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

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

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: color 0.15s ease;
}

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

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

img,
svg {
  vertical-align: middle;
  max-width: 100%;
}

code,
pre,
kbd,
samp,
.mono {
  font-family: var(--font-mono);
}

code {
  font-size: 0.875em;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  padding: 0.12em 0.35em;
  border-radius: var(--radius-sm);
}

pre {
  background-color: var(--code-bg);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  font-size: 0.875rem;
  line-height: 1.55;
  margin: 1.25rem 0;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: inherit;
}

/* Accessibility Skip Link */
.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  background: var(--accent-primary);
  color: #0b0f17;
  font-weight: 600;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  z-index: 1000;
}

.skip-link:focus {
  top: 0.75rem;
}

/* Layout Containers */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

main {
  flex: 1 0 auto;
  padding-bottom: 3.5rem;
}

/* Top Utility Bar */
.utility-bar {
  background-color: var(--bg-inset);
  border-bottom: 1px solid var(--border-subtle);
  font-size: 0.78rem;
  color: var(--text-muted);
  padding: 0.4rem 0;
}

.utility-bar-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.utility-status {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
}

.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background-color: var(--accent-emerald);
  display: inline-block;
}

.status-dot.warning {
  background-color: var(--accent-amber);
}

.utility-links {
  display: flex;
  align-items: center;
  gap: 1rem;
  font-family: var(--font-mono);
}

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

.utility-links a:hover {
  color: var(--text-primary);
}

/* Site Header & Masthead */
.site-header {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-default);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 4rem;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-primary);
  text-decoration: none;
}

.brand:hover {
  text-decoration: none;
  color: var(--text-primary);
}

.brand-mark {
  width: 34px;
  height: 34px;
  flex-shrink: 0;
}

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

.brand-title {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.brand-subtitle {
  font-size: 0.72rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  letter-spacing: 0.01em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.nav-link {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.45rem 0.8rem;
  border-radius: var(--radius-sm);
  transition: background-color 0.15s ease, color 0.15s ease;
}

.nav-link:hover {
  background-color: var(--bg-hover);
  color: var(--text-primary);
  text-decoration: none;
}

.nav-link[aria-current="page"] {
  background-color: var(--accent-primary-subtle);
  color: var(--accent-primary);
  font-weight: 600;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.theme-toggle {
  background: var(--bg-elevated);
  border: 1px solid var(--border-default);
  color: var(--text-secondary);
  padding: 0.4rem 0.7rem;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-family: var(--font-mono);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  transition: border-color 0.15s ease, background-color 0.15s ease;
}

.theme-toggle:hover {
  background: var(--bg-hover);
  border-color: var(--border-strong);
  color: var(--text-primary);
}

/* Editorial Hero */
.editorial-hero {
  padding: 2.5rem 0 2rem;
  border-bottom: 1px solid var(--border-default);
  background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 2rem;
  align-items: start;
}

.hero-kicker {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-amber);
  background-color: var(--accent-amber-subtle);
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  margin-bottom: 0.85rem;
}

.hero-title {
  font-size: clamp(1.75rem, 3vw, 2.35rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.2;
  margin: 0 0 0.85rem;
}

.hero-lead {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 64ch;
  margin: 0 0 1.25rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.hero-panel {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 1.25rem;
}

.hero-panel-title {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin: 0 0 0.75rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.quick-tool-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.5rem;
}

.quick-tool-item a {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.55rem 0.75rem;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.88rem;
  font-weight: 500;
  transition: border-color 0.15s ease, transform 0.1s ease;
}

.quick-tool-item a:hover {
  border-color: var(--accent-primary);
  text-decoration: none;
}

.quick-tool-tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-muted);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.55rem 1.05rem;
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
  font-family: var(--font-sans);
}

.btn:hover {
  text-decoration: none;
}

.btn-primary {
  background-color: var(--accent-primary);
  color: #090d14;
}

.btn-primary:hover {
  background-color: var(--accent-primary-hover);
  color: #090d14;
}

.btn-secondary {
  background-color: var(--bg-elevated);
  border-color: var(--border-default);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background-color: var(--bg-hover);
  border-color: var(--border-strong);
}

.btn-sm {
  padding: 0.35rem 0.7rem;
  font-size: 0.8rem;
}

/* Section Headers */
.section-block {
  margin-top: 2.5rem;
}

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  border-bottom: 1px solid var(--border-default);
  padding-bottom: 0.65rem;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.section-title {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.015em;
  margin: 0;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.section-meta {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

/* Editorial Two-Column Layout on Home */
.editorial-columns {
  display: grid;
  grid-template-columns: 1.65fr 1fr;
  gap: 2rem;
  align-items: start;
}

/* Transparency Banner */
.editorial-notice {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-left: 3px solid var(--accent-primary);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1.1rem;
  margin-bottom: 1.25rem;
  font-size: 0.86rem;
  color: var(--text-secondary);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* Story Feed List */
.story-list {
  list-style: none;
  padding: 0;
  margin: 0;
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  background-color: var(--bg-secondary);
  divide-y: 1px solid var(--border-subtle);
}

.story-item {
  padding: 0.95rem 1.15rem;
  border-bottom: 1px solid var(--border-subtle);
  transition: background-color 0.12s ease;
}

.story-item:last-child {
  border-bottom: none;
}

.story-item:hover {
  background-color: var(--bg-elevated);
}

.story-top {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.35rem;
}

.story-title {
  font-size: 0.98rem;
  font-weight: 600;
  line-height: 1.4;
  margin: 0;
}

.story-title a {
  color: var(--text-primary);
}

.story-title a:hover {
  color: var(--accent-primary);
}

.story-domain {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-faint);
  white-space: nowrap;
}

.story-summary {
  font-size: 0.86rem;
  color: var(--text-muted);
  margin: 0.25rem 0 0.45rem;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.story-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.65rem;
  font-size: 0.76rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

/* Category & Source Badges */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.12rem 0.48rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  border: 1px solid var(--border-default);
  background-color: var(--bg-elevated);
  color: var(--text-secondary);
}

.badge-cat-Open-Source {
  border-color: rgba(56, 189, 248, 0.35);
  color: var(--cat-opensource);
}

.badge-cat-Development {
  border-color: rgba(167, 139, 250, 0.35);
  color: var(--cat-dev);
}

.badge-cat-Infrastructure {
  border-color: rgba(245, 158, 11, 0.35);
  color: var(--cat-infra);
}

.badge-cat-Security {
  border-color: rgba(244, 63, 94, 0.35);
  color: var(--cat-security);
}

.badge-cat-Linux {
  border-color: rgba(16, 185, 129, 0.35);
  color: var(--cat-linux);
}

.badge-release {
  background-color: var(--accent-emerald-subtle);
  color: var(--accent-emerald);
  border-color: rgba(16, 185, 129, 0.3);
}

/* Release Cards Sidebar */
.release-list {
  display: grid;
  gap: 0.65rem;
  list-style: none;
  padding: 0;
  margin: 0;
}

.release-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 0.85rem 1rem;
  transition: border-color 0.15s ease;
}

.release-card:hover {
  border-color: var(--border-strong);
}

.release-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.3rem;
}

.release-project {
  font-size: 0.78rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
}

.release-title {
  font-size: 0.92rem;
  font-weight: 600;
  margin: 0 0 0.3rem;
}

.release-title a {
  color: var(--text-primary);
}

.release-title a:hover {
  color: var(--accent-primary);
}

/* Card Grids for Tools & Guides */
.card-grid-4 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}

.card-grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(310px, 1fr));
  gap: 1.25rem;
}

.feature-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.feature-card:hover {
  border-color: var(--border-strong);
  box-shadow: var(--shadow-sm);
}

.feature-card-kicker {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--accent-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.45rem;
}

.feature-card-title {
  font-size: 1.08rem;
  font-weight: 700;
  margin: 0 0 0.5rem;
}

.feature-card-title a {
  color: var(--text-primary);
}

.feature-card-title a:hover {
  color: var(--accent-primary);
}

.feature-card-desc {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin: 0 0 1rem;
  flex-grow: 1;
}

.feature-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-subtle);
  font-family: var(--font-mono);
  font-size: 0.78rem;
}

/* Filter & Search Bar (/news/) */
.filter-bar {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 1rem;
  margin-bottom: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.filter-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  justify-content: space-between;
}

.category-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.cat-pill {
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-default);
  color: var(--text-secondary);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 500;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: all 0.15s ease;
}

.cat-pill:hover {
  border-color: var(--border-strong);
  color: var(--text-primary);
}

.cat-pill.active {
  background-color: var(--accent-primary);
  border-color: var(--accent-primary);
  color: #090d14;
  font-weight: 600;
}

.search-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  flex: 1;
  min-width: 260px;
}

.input-control,
.select-control,
.textarea-control {
  background-color: var(--bg-inset);
  border: 1px solid var(--border-default);
  color: var(--text-primary);
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-family: var(--font-sans);
  transition: border-color 0.15s ease;
}

.input-control:focus,
.select-control:focus,
.textarea-control:focus {
  border-color: var(--accent-primary);
  outline: none;
}

.textarea-control {
  width: 100%;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.5;
  resize: vertical;
  min-height: 170px;
}

/* Pagination */
.pagination-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 1.25rem;
  padding: 0.75rem 1rem;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

/* Empty, Loading & Fallback States */
.state-box {
  background-color: var(--bg-secondary);
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius-md);
  padding: 2.25rem 1.5rem;
  text-align: center;
  color: var(--text-muted);
}

.state-box-title {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0 0 0.4rem;
}

.state-box-desc {
  font-size: 0.9rem;
  max-width: 52ch;
  margin: 0 auto 1rem;
}

/* ==========================================================================
   Edge Tools Workbench (/tools/)
   ========================================================================== */

.tools-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-default);
  padding-bottom: 1rem;
}

.tool-tab-btn {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  color: var(--text-secondary);
  padding: 0.6rem 1.1rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.15s ease;
}

.tool-tab-btn:hover {
  border-color: var(--border-strong);
  color: var(--text-primary);
}

.tool-tab-btn[aria-selected="true"] {
  background-color: var(--accent-primary-subtle);
  border-color: var(--accent-primary);
  color: var(--accent-primary);
}

.tool-section {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  margin-bottom: 2rem;
}

.tool-section[hidden] {
  display: none;
}

.tool-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 1rem;
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 1rem;
  margin-bottom: 1.25rem;
}

.tool-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin: 0 0 0.3rem;
}

.tool-subtitle {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin: 0;
}

.tool-presets {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  align-items: center;
}

.preset-btn {
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-default);
  color: var(--text-secondary);
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  cursor: pointer;
}

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

.tool-workbench-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

.form-group {
  margin-bottom: 1rem;
}

.form-label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--text-secondary);
}

.form-hint {
  font-size: 0.76rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  font-weight: 400;
}

.tool-actions-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin: 0.75rem 0;
}

.alert-banner {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.86rem;
  font-family: var(--font-mono);
  margin: 0.75rem 0;
  border: 1px solid transparent;
}

.alert-error {
  background-color: var(--accent-rose-subtle);
  border-color: rgba(244, 63, 94, 0.4);
  color: var(--accent-rose);
}

.alert-success {
  background-color: var(--accent-emerald-subtle);
  border-color: rgba(16, 185, 129, 0.4);
  color: var(--accent-emerald);
}

.alert-info {
  background-color: var(--accent-primary-subtle);
  border-color: rgba(56, 189, 248, 0.35);
  color: var(--accent-primary);
}

/* Key-Value Output Table (Subnet Calculator & SHA-256) */
.kv-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  border: 1px solid var(--border-default);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.kv-table th,
.kv-table td {
  padding: 0.6rem 0.85rem;
  border-bottom: 1px solid var(--border-subtle);
  text-align: left;
}

.kv-table th {
  width: 36%;
  background-color: var(--bg-elevated);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.82rem;
}

.kv-table td {
  font-family: var(--font-mono);
  color: var(--text-primary);
  background-color: var(--bg-inset);
  word-break: break-all;
}

.kv-table tr:last-child th,
.kv-table tr:last-child td {
  border-bottom: none;
}

.bitmask-box {
  background-color: var(--code-bg);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-sm);
  padding: 0.75rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  overflow-x: auto;
  margin-top: 1rem;
}

.bit-net {
  color: var(--accent-primary);
  font-weight: 700;
}

.bit-host {
  color: var(--accent-amber);
}

/* ==========================================================================
   Educational Articles & Guides (/guides/)
   ========================================================================== */

.article-layout {
  display: grid;
  grid-template-columns: minmax(0, var(--reading-width)) 260px;
  gap: 3rem;
  justify-content: space-between;
  align-items: start;
  margin-top: 2rem;
}

.article-prose {
  font-size: 1.02rem;
  line-height: 1.72;
  color: var(--text-secondary);
}

.article-prose h1 {
  font-size: clamp(1.7rem, 2.8vw, 2.25rem);
  color: var(--text-primary);
  line-height: 1.22;
  letter-spacing: -0.02em;
  margin: 0 0 0.75rem;
}

.article-prose h2 {
  font-size: 1.38rem;
  color: var(--text-primary);
  margin: 2.2rem 0 0.75rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--border-subtle);
}

.article-prose h3 {
  font-size: 1.12rem;
  color: var(--text-primary);
  margin: 1.6rem 0 0.5rem;
}

.article-prose p {
  margin: 0 0 1.15rem;
}

.article-prose ul,
.article-prose ol {
  margin: 0 0 1.25rem;
  padding-left: 1.5rem;
}

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

.article-prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.88rem;
}

.article-prose th,
.article-prose td {
  border: 1px solid var(--border-default);
  padding: 0.55rem 0.75rem;
  text-align: left;
}

.article-prose th {
  background-color: var(--bg-elevated);
  color: var(--text-primary);
}

.callout-box {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-left: 3px solid var(--accent-amber);
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  font-size: 0.92rem;
}

.callout-box strong {
  color: var(--text-primary);
  display: block;
  margin-bottom: 0.25rem;
}

.toc-sidebar {
  position: sticky;
  top: 5.25rem;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 1.1rem;
  font-size: 0.85rem;
}

.toc-title {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin: 0 0 0.65rem;
}

.toc-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.4rem;
}

.toc-list a {
  color: var(--text-secondary);
  display: block;
  padding: 0.2rem 0;
}

.toc-list a:hover {
  color: var(--accent-primary);
}

/* Page Header Banner (Subpages) */
.page-header {
  padding: 2rem 0 1.5rem;
  border-bottom: 1px solid var(--border-default);
  background-color: var(--bg-secondary);
}

.page-title {
  font-size: clamp(1.5rem, 2.5vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 0.4rem;
}

.page-desc {
  color: var(--text-muted);
  font-size: 0.98rem;
  max-width: 68ch;
  margin: 0;
}

/* Site Footer */
.site-footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-default);
  padding: 2.5rem 0 2rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(3, 1fr);
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-col-title {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-primary);
  margin: 0 0 0.75rem;
}

.footer-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.4rem;
}

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

.footer-links a:hover {
  color: var(--text-primary);
}

.footer-bottom {
  border-top: 1px solid var(--border-subtle);
  padding-top: 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  font-size: 0.8rem;
}

/* Responsive Breakpoints */
@media (max-width: 960px) {
  .hero-grid,
  .editorial-columns,
  .tool-workbench-grid,
  .article-layout {
    grid-template-columns: 1fr;
  }

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

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

@media (max-width: 640px) {
  .header-inner {
    flex-wrap: wrap;
    padding: 0.6rem 0;
  }

  .site-nav {
    width: 100%;
    overflow-x: auto;
    padding-bottom: 0.25rem;
  }

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

  .kv-table th,
  .kv-table td {
    display: block;
    width: 100%;
  }
}