:root {
  --bg-page: #f8fafc;
  --bg-surface: #ffffff;
  --bg-subtle: #f1f5f9;
  --bg-code: #0f172a;
  --text-primary: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --border-strong: #cbd5e1;
  --accent-primary: #0284c7;
  --accent-hover: #0369a1;
  --accent-subtle: #e0f2fe;
  --status-ok: #059669;
  --status-ok-bg: #ecfdf5;
  --status-warn: #d97706;
  --status-warn-bg: #fffbeb;
  --status-crit: #dc2626;
  --status-crit-bg: #fef2f2;
  --font-sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.05);
  --radius-sm: 5px;
  --radius-md: 8px;
}

[data-theme="dark"] {
  --bg-page: #0b0f17;
  --bg-surface: #131b2e;
  --bg-subtle: #1e293b;
  --bg-code: #060911;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border-color: #26334d;
  --border-strong: #334155;
  --accent-primary: #38bdf8;
  --accent-hover: #7dd3fc;
  --accent-subtle: #0c4a6e;
  --status-ok: #10b981;
  --status-ok-bg: rgba(16, 185, 129, 0.14);
  --status-warn: #f59e0b;
  --status-warn-bg: rgba(245, 158, 11, 0.14);
  --status-crit: #ef4444;
  --status-crit-bg: rgba(239, 68, 68, 0.14);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-page);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

a:hover {
  text-decoration: underline;
}

/* Header & Clean Wrap Navigation (Zero Scrollbar) */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}

.header-inner {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0.7rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  text-decoration: none !important;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.38rem;
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  color: #ffffff;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.86rem;
  letter-spacing: 0.04em;
  padding: 0.45rem 0.7rem;
  border-radius: 7px;
  border: 1px solid #334155;
  box-shadow: 0 2px 8px rgba(15, 23, 42, 0.18);
  position: relative;
  overflow: hidden;
  transition: transform 0.15s ease, border-color 0.15s ease;
}

.brand-mark::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, #f97316, #ef4444, #0284c7);
}

.brand:hover .brand-mark {
  transform: translateY(-1px);
  border-color: #f97316;
}

.brand-icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

.brand-text {
  display: flex;
  flex-direction: column;
  gap: 0.14rem;
}

.brand-name {
  font-weight: 700;
  font-size: 1.24rem;
  color: var(--text-primary);
  letter-spacing: -0.025em;
  line-height: 1.1;
}

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

.brand-domain {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: #ea580c;
  margin-left: 1px;
}

.brand-tag {
  display: flex;
  align-items: center;
  gap: 0.42rem;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.tag-fire {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #ffffff;
  background: linear-gradient(135deg, #ea580c, #dc2626);
  padding: 0.08rem 0.42rem;
  border-radius: 3px;
}

/* Primary Nav Bar - Clean Flex Wrap, No Horizontal Scrollbar */
.main-nav {
  background: var(--bg-subtle);
  border-top: 1px solid var(--border-color);
}

.main-nav-inner {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 1.25rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem;
}

.nav-link {
  display: inline-block;
  padding: 0.55rem 0.85rem;
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--text-secondary);
  border-bottom: 2px solid transparent;
  text-decoration: none !important;
  transition: color 0.15s, background 0.15s;
}

.nav-link:hover {
  color: var(--accent-primary);
  background: var(--bg-surface);
}

.nav-link.active {
  color: var(--accent-primary);
  border-bottom-color: var(--accent-primary);
  background: var(--bg-surface);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 600;
  padding: 0.42rem 0.85rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: var(--bg-surface);
  color: var(--text-primary);
  cursor: pointer;
  text-decoration: none !important;
  transition: background 0.15s, border-color 0.15s;
}

.btn:hover {
  background: var(--bg-subtle);
}

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

.btn-primary:hover {
  background: var(--accent-hover);
}

/* CLS-Safe AdSense Slots (Hidden until AdSense Publisher ID is live) */
.ad-container {
  display: none !important; /* Remove this line when enabling live AdSense ads */
  background: var(--bg-surface);
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 0.5rem;
  margin: 1rem auto;
  text-align: center;
}

.ad-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.2rem;
}

.ad-leaderboard {
  max-width: 1360px;
  min-height: 90px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.ad-in-article {
  min-height: 110px;
  margin: 1.5rem 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.ad-sidebar {
  min-height: 250px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.ad-placeholder-inner {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--text-muted);
  padding: 0.5rem;
}

/* 3-Column Learning Portal Layout */
.portal-layout {
  max-width: 1360px;
  margin: 0 auto;
  padding: 1.25rem;
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr) 300px;
  gap: 1.5rem;
  align-items: start;
}

/* Left Sidebar: Full 12-Topic Course Curriculum */
.left-rail {
  position: sticky;
  top: 110px;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
}

.rail-title {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
  font-weight: 700;
}

.course-group-title {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-muted);
  margin: 0.75rem 0 0.3rem;
  padding-left: 0.4rem;
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.toc-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.4rem 0.55rem;
  font-size: 0.82rem;
  color: var(--text-secondary);
  border-left: 3px solid transparent;
  border-radius: var(--radius-sm);
  text-decoration: none !important;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.toc-link:hover {
  background: var(--bg-subtle);
  color: var(--accent-primary);
}

.toc-link.active {
  background: var(--accent-subtle);
  color: var(--accent-primary);
  border-left-color: var(--accent-primary);
  font-weight: 600;
}

article[id],
section[id] {
  scroll-margin-top: 115px;
}

/* Main Column */
.main-column {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.hero-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--accent-primary);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}

.hero-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--accent-primary);
  text-transform: uppercase;
  font-weight: 700;
  margin-bottom: 0.35rem;
}

.hero-title {
  font-size: 1.65rem;
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 0.5rem;
}

.hero-subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
  max-width: 72ch;
}

.quick-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.75rem;
  padding-top: 1rem;
  margin-top: 1rem;
  border-top: 1px solid var(--border-color);
}

.stat-item {
  background: var(--bg-subtle);
  padding: 0.6rem 0.75rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.stat-val {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
}

.stat-lbl {
  font-size: 0.74rem;
  color: var(--text-muted);
}

.filter-bar {
  display: flex;
  gap: 0.45rem;
  flex-wrap: wrap;
  margin-bottom: 0.85rem;
}

.filter-btn {
  padding: 0.35rem 0.7rem;
  font-size: 0.78rem;
  font-family: var(--font-mono);
  font-weight: 600;
  border: 1px solid var(--border-strong);
  background: var(--bg-subtle);
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  cursor: pointer;
}

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

.module-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}

.module-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  padding-bottom: 0.75rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}

.module-id {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--accent-primary);
  background: var(--accent-subtle);
  padding: 0.15rem 0.45rem;
  border-radius: 3px;
  display: inline-block;
  margin-bottom: 0.3rem;
}

.module-title {
  font-size: 1.25rem;
  font-weight: 700;
}

.simple-explain {
  background: var(--accent-subtle);
  border-left: 4px solid var(--accent-primary);
  padding: 0.85rem 1rem;
  font-size: 0.9rem;
  color: var(--text-primary);
  margin-bottom: 1.15rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.simple-explain strong {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  text-transform: uppercase;
  margin-right: 0.35rem;
}

/* Grids & Cards */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.9rem;
}

.info-box {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 1rem;
  background: var(--bg-page);
}

.info-box h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.45rem;
  color: var(--text-primary);
}

.info-box p,
.info-box li {
  font-size: 0.86rem;
  color: var(--text-secondary);
}

.info-box ul {
  padding-left: 1.15rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

/* Course Card Links on Home Page */
.course-card {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.1rem;
  background: var(--bg-surface);
  transition: border-color 0.15s, transform 0.15s;
  text-decoration: none !important;
  color: inherit;
}

.course-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-2px);
}

.course-card h3 {
  font-size: 1rem;
  color: var(--text-primary);
  margin: 0.3rem 0 0.4rem;
}

.course-card p {
  font-size: 0.84rem;
  color: var(--text-secondary);
  margin-bottom: 0.8rem;
}

.course-card-footer {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--accent-primary);
}

/* Tables */
.table-wrap {
  overflow-x: auto;
  margin: 0.85rem 0;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  text-align: left;
}

th {
  background: var(--bg-subtle);
  color: var(--text-primary);
  font-weight: 700;
  padding: 0.65rem 0.75rem;
  border-bottom: 1px solid var(--border-strong);
  font-size: 0.78rem;
}

td {
  padding: 0.65rem 0.75rem;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-secondary);
  vertical-align: top;
}

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

code {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  background: var(--bg-subtle);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  color: var(--text-primary);
}

pre {
  background: var(--bg-code);
  color: #e2e8f0;
  font-family: var(--font-mono);
  font-size: 0.79rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius-sm);
  overflow-x: auto;
  line-height: 1.55;
  margin: 0.75rem 0;
}

/* Interview Q&A Cards */
.qa-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.qa-item {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.95rem 1.1rem;
  background: var(--bg-page);
}

.qa-q {
  font-weight: 700;
  font-size: 0.92rem;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}

.qa-tag {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  background: var(--accent-subtle);
  color: var(--accent-primary);
  padding: 0.1rem 0.4rem;
  border-radius: 3px;
  flex-shrink: 0;
}

.qa-a {
  font-size: 0.86rem;
  color: var(--text-secondary);
}

/* Badges */
.badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  padding: 0.12rem 0.45rem;
  border-radius: 3px;
}

.badge-ok {
  background: var(--status-ok-bg);
  color: var(--status-ok);
}

.badge-warn {
  background: var(--status-warn-bg);
  color: var(--status-warn);
}

.badge-crit {
  background: var(--status-crit-bg);
  color: var(--status-crit);
}

/* Interactive Calculator & Checkboxes & Quiz */
.calc-panel {
  margin-top: 1rem;
  background: var(--bg-subtle);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 1rem;
}

.calc-controls {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.85rem;
  margin: 0.75rem 0;
}

.field-group label {
  display: block;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.3rem;
}

.field-group select,
.field-group input {
  width: 100%;
  padding: 0.45rem 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  color: var(--text-primary);
}

.calc-results {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.65rem;
  margin-top: 0.75rem;
}

.calc-stat {
  background: var(--bg-surface);
  padding: 0.65rem 0.8rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.calc-stat-label {
  font-size: 0.72rem;
  color: var(--text-muted);
}

.calc-stat-val {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  color: var(--accent-primary);
}

.check-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.5rem;
  margin-top: 0.5rem;
}

.check-item {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  font-size: 0.84rem;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0.45rem 0.6rem;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
}

.check-item input {
  margin-top: 0.22rem;
  accent-color: var(--accent-primary);
}

.quiz-box {
  background: var(--bg-subtle);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 1.15rem;
}

.quiz-question {
  font-size: 0.98rem;
  font-weight: 600;
  margin-bottom: 0.85rem;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.quiz-opt {
  text-align: left;
  padding: 0.65rem 0.85rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.86rem;
  color: var(--text-primary);
  cursor: pointer;
}

.quiz-opt:hover:not(:disabled) {
  border-color: var(--accent-primary);
  background: var(--accent-subtle);
}

.quiz-opt.correct {
  border-color: var(--status-ok);
  background: var(--status-ok-bg);
  font-weight: 600;
}

.quiz-opt.wrong {
  border-color: var(--status-crit);
  background: var(--status-crit-bg);
}

.quiz-feedback {
  margin-top: 0.85rem;
  padding: 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  background: var(--bg-surface);
  border-left: 3px solid var(--accent-primary);
  display: none;
}

/* Lesson Prev / Next Pagination Bar */
.lesson-pager {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 1.1rem 1.25rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
}

.pager-link {
  display: flex;
  flex-direction: column;
  text-decoration: none !important;
  padding: 0.4rem 0.6rem;
  border-radius: var(--radius-sm);
}

.pager-link:hover {
  background: var(--bg-subtle);
}

.pager-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
}

.pager-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--accent-primary);
}

/* Right Rail */
.right-rail {
  position: sticky;
  top: 110px;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.rail-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
}

.rail-card h3 {
  font-size: 0.9rem;
  font-weight: 700;
  margin-bottom: 0.45rem;
}

.cheat-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 0.8rem;
}

.cheat-list li {
  display: flex;
  justify-content: space-between;
  border-bottom: 1px dashed var(--border-color);
  padding-bottom: 0.3rem;
}

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

.quick-links a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.42rem 0.6rem;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-page);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  text-decoration: none !important;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}

.quick-links a:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: var(--accent-subtle);
}

/* 4-Column Quiz Category Grid & 20-Question Objective Assessment */
.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.85rem;
}

.quiz-cat-card {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.9rem;
  background: var(--bg-page);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 0.5rem;
  transition: border-color 0.15s, transform 0.15s;
}

.quiz-cat-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-1px);
}

.quiz-cat-card h3 {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.quiz-cat-card p {
  font-size: 0.78rem;
  color: var(--text-secondary);
  line-height: 1.45;
}

.quiz-cat-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-muted);
  padding-top: 0.45rem;
  border-top: 1px dashed var(--border-color);
}

.obj-q-card {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 1rem 1.1rem;
  background: var(--bg-page);
  margin-bottom: 0.9rem;
}

.obj-q-title {
  font-size: 0.93rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.65rem;
}

.obj-opt-list {
  display: flex;
  flex-direction: column;
  gap: 0.42rem;
}

.obj-opt-label {
  display: flex;
  align-items: flex-start;
  gap: 0.55rem;
  padding: 0.5rem 0.7rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  font-size: 0.85rem;
  color: var(--text-primary);
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
}

.obj-opt-label:hover {
  border-color: var(--accent-primary);
  background: var(--accent-subtle);
}

.obj-opt-label input[type="radio"] {
  margin-top: 0.22rem;
  accent-color: var(--accent-primary);
}

.obj-opt-label.is-correct {
  border-color: var(--status-ok);
  background: var(--status-ok-bg);
  font-weight: 600;
}

.obj-opt-label.is-wrong {
  border-color: var(--status-crit);
  background: var(--status-crit-bg);
}

.obj-explain-box {
  margin-top: 0.7rem;
  padding: 0.75rem 0.9rem;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border-left: 4px solid var(--accent-primary);
  font-size: 0.84rem;
  color: var(--text-secondary);
  display: none;
}

/* Footer */
.site-footer {
  margin-top: 2.5rem;
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 2rem 1.25rem;
  font-size: 0.82rem;
  color: var(--text-muted);
}

.footer-inner {
  max-width: 1360px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2rem;
}

.footer-col h4 {
  font-size: 0.8rem;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
  font-family: var(--font-mono);
  text-transform: uppercase;
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

@media (max-width: 1100px) {
  .portal-layout {
    grid-template-columns: 220px minmax(0, 1fr);
  }
  .right-rail {
    grid-column: 1 / -1;
    position: static;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
  }
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 780px) {
  .portal-layout {
    grid-template-columns: 1fr;
  }
  .right-rail,
  .grid-2,
  .grid-3,
  .grid-4,
  .calc-controls,
  .calc-results,
  .check-grid,
  .footer-inner {
    grid-template-columns: 1fr;
  }
}