:root {
  color-scheme: light;

  --bg: #f1f5f9;
  --panel: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --border: #e2e8f0;

  --primary: #2563eb;
  --primary-light: #dbeafe;
  --success: #16a34a;
  --success-light: #dcfce7;
  --warning: #d97706;
  --warning-light: #fef3c7;
  --danger: #dc2626;
  --danger-light: #fee2e2;
  --focus: #0ea5e9;

  --radius: 12px;
  --space-1: 8px;
  --space-2: 12px;
  --space-3: 16px;
  --space-4: 24px;

  --sidebar-width: 240px;
  --topbar-height: 56px;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0b1220;
  --panel: #0f172a;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --border: #22314d;
  --primary: #60a5fa;
  --primary-light: #1e3a5f;
  --success: #4ade80;
  --success-light: #14532d;
  --warning: #fbbf24;
  --warning-light: #713f12;
  --danger: #f87171;
  --danger-light: #7f1d1d;
  --focus: #38bdf8;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  line-height: 1.5;
}

a { color: inherit; text-decoration: none; }
a:hover { text-decoration: underline; }

.skip-link {
  position: absolute;
  left: -9999px;
  top: var(--space-2);
  padding: var(--space-2);
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
}

.skip-link:focus {
  left: var(--space-2);
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

/* ===== TOP BAR ===== */
.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 10;
  height: var(--topbar-height);
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  padding: 0 var(--space-4);
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.topbar__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 17px;
}

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

.brand__icon { font-size: 24px; }

.topbar__user {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: 13px;
}

.user__name { color: var(--text); }
.user__status { font-size: 11px; }

.topbar__actions {
  display: flex;
  gap: var(--space-2);
}

/* ===== APP SHELL (sidebar + main) ===== */
.app-shell {
  display: flex;
  padding-top: var(--topbar-height);
  min-height: 100vh;
}

/* ===== SIDEBAR ===== */
.sidebar {
  position: fixed;
  top: var(--topbar-height);
  left: 0;
  bottom: 0;
  width: var(--sidebar-width);
  background: var(--panel);
  border-right: 1px solid var(--border);
  padding: var(--space-3) 0;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

.sidebar__section {
  padding: var(--space-2) var(--space-3);
}

.sidebar__heading {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--muted);
  margin-bottom: var(--space-1);
  padding: 0 var(--space-2);
}

.sidebar__link {
  display: block;
  padding: 10px var(--space-2);
  border-radius: 10px;
  color: var(--muted);
  font-size: 14px;
  margin-bottom: 2px;
}

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

.sidebar__link[aria-current="page"] {
  background: var(--primary-light);
  color: var(--primary);
  font-weight: 600;
}

.sidebar__footer {
  margin-top: auto;
  padding: var(--space-3);
}

/* ===== MAIN CONTENT ===== */
.main {
  margin-left: var(--sidebar-width);
  flex: 1;
  padding: var(--space-4);
  min-width: 0;
}

.page {
  max-width: 1100px;
}

@media (max-width: 800px) {
  .sidebar { display: none; }
  .main { margin-left: 0; }
}

/* ===== CARDS ===== */
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-4);
}

.card__title {
  margin: 0 0 var(--space-3) 0;
  font-size: 18px;
  font-weight: 700;
}

/* ===== STAT CARDS (dashboard) ===== */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}

.stat-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-3);
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.stat-card__label {
  font-size: 12px;
  color: var(--muted);
}

.stat-card__value {
  font-size: 28px;
  font-weight: 700;
}

.stat-card__sub {
  font-size: 12px;
  color: var(--muted);
}

/* ===== ACTION CARDS (dashboard) ===== */
.action-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-3);
}

.action-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  cursor: pointer;
  transition: box-shadow 0.15s, border-color 0.15s;
}

.action-card:hover {
  border-color: var(--primary);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.1);
  text-decoration: none;
}

.action-card__icon {
  font-size: 32px;
}

.action-card__title {
  font-weight: 700;
  font-size: 16px;
}

.action-card__desc {
  font-size: 13px;
  color: var(--muted);
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-4);
}

.card__title {
  margin: 0 0 var(--space-3) 0;
  font-size: 18px;
}

.row {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
  align-items: center;
}

.field {
  display: grid;
  gap: 6px;
  margin-bottom: var(--space-3);
}

.field__label {
  color: var(--muted);
  font-size: 12px;
}

.input {
  width: 100%;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
}

.input:focus {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.btn {
  border: 1px solid var(--border);
  background: var(--primary);
  color: white;
  padding: 10px 12px;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 600;
}

.btn:focus {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.btn--secondary {
  background: transparent;
  color: var(--text);
}

.btn--ghost {
  background: transparent;
  color: var(--text);
}

.btn--danger {
  background: var(--danger);
  color: white;
  border-color: transparent;
}

.btn--icon {
  background: transparent;
  border: none;
  font-size: 18px;
  padding: 6px 10px;
}

.muted { color: var(--muted); font-size: 13px; }

.kv {
  display: grid;
  gap: 8px;
  margin-bottom: var(--space-3);
}

.kv__row {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: var(--space-2);
  font-size: 13px;
}

.kv__k { color: var(--muted); }
.kv__v { overflow-wrap: anywhere; }

.code {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: var(--space-3);
  background: var(--bg);
  margin: 0;
  max-height: 260px;
  overflow: auto;
  font-size: 12px;
}

.table-wrap {
  width: 100%;
  overflow: auto;
  border: 1px solid var(--border);
  border-radius: 12px;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
}

th, td {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

th {
  color: var(--muted);
  font-weight: 700;
  background: var(--bg);
  position: sticky;
  top: 0;
}

.badge {
  display: inline-block;
  padding: 2px 10px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 12px;
  color: var(--muted);
}

.badge--ok { color: var(--text); }
.badge--warn { color: var(--text); }
.badge--danger { color: var(--text); }

.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.45);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 50;
  padding: var(--space-4);
}

.modal {
  width: min(720px, 100%);
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: var(--space-4);
}

.modal__title { margin: 0 0 var(--space-3) 0; font-size: 16px; }

.spinner {
  width: 18px;
  height: 18px;
  border-radius: 999px;
  border: 2px solid var(--border);
  border-top-color: var(--primary);
  animation: spin 0.8s linear infinite;
  display: inline-block;
}

@keyframes spin { to { transform: rotate(360deg); } }

.toast-region {
  position: fixed;
  right: var(--space-4);
  top: 84px;
  display: grid;
  gap: 8px;
  z-index: 20;
}

.toast {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 10px 12px;
  min-width: 240px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.toast__title {
  font-weight: 700;
  font-size: 13px;
  margin-bottom: 4px;
}

.toast__body {
  font-size: 12px;
  color: var(--muted);
}

.footer {
  padding: var(--space-4);
  border-top: 1px solid var(--border);
  text-align: center;
}

/* ===== TOGGLE SWITCH ===== */
.toggle {
  display: inline-flex;
  align-items: center;
  cursor: pointer;
}

.toggle input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.toggle__slider {
  width: 36px;
  height: 20px;
  background: var(--border);
  border-radius: 10px;
  position: relative;
  transition: background 0.2s;
}

.toggle__slider::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  background: var(--panel);
  border-radius: 50%;
  transition: transform 0.2s;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

.toggle input:checked + .toggle__slider {
  background: var(--primary);
}

.toggle input:checked + .toggle__slider::after {
  transform: translateX(16px);
}

.toggle input:focus + .toggle__slider {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

/* ===== MODAL OVERLAY (v2) ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 50;
  padding: var(--space-4);
}

.modal-overlay[hidden] { display: none; }

.modal__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-3);
}

.modal__title { margin: 0; font-size: 16px; font-weight: 700; }

.modal__close {
  background: transparent;
  border: none;
  font-size: 22px;
  cursor: pointer;
  color: var(--muted);
  line-height: 1;
}

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

.modal__body { margin-bottom: var(--space-3); }

.modal__footer {
  display: flex;
  justify-content: flex-end;
  gap: var(--space-2);
}

/* ===== BUTTON SIZES ===== */
.btn--sm {
  padding: 6px 10px;
  font-size: 12px;
}

/* ===== BADGES IMPROVEMENTS ===== */
.badge--ok { background: var(--success-light); color: var(--success); border-color: var(--success); }
.badge--error { background: var(--danger-light); color: var(--danger); border-color: var(--danger); }

/* ===== SCENARIOS PAGE ===== */
.scenarios-page {
  padding: var(--space-4);
  max-width: 1400px;
  margin: 0 auto;
}

/* Hero Section */
.hero-section {
  background: linear-gradient(135deg, var(--primary) 0%, #1d4ed8 100%);
  color: white;
  border-radius: var(--radius);
  padding: var(--space-4) var(--space-4) calc(var(--space-4) + 40px);
  margin-bottom: var(--space-4);
  text-align: center;
}

.hero-section h1 {
  font-size: 2.2rem;
  margin-bottom: var(--space-2);
}

.hero-subtitle {
  font-size: 1.1rem;
  opacity: 0.9;
  max-width: 700px;
  margin: 0 auto var(--space-3);
  line-height: 1.6;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-3);
  flex-wrap: wrap;
}

.stat-card {
  background: rgba(255,255,255,0.15);
  border-radius: var(--radius);
  padding: var(--space-3);
  min-width: 140px;
  backdrop-filter: blur(10px);
}

.stat-number {
  display: block;
  font-size: 2.5rem;
  font-weight: 700;
}

.stat-label {
  font-size: 0.9rem;
  opacity: 0.9;
}

/* How It Works */
.how-it-works {
  margin-bottom: var(--space-4);
}

.how-it-works h2 {
  margin-bottom: var(--space-3);
  color: var(--text);
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-3);
}

.step-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-3);
  text-align: center;
}

.step-number {
  width: 40px;
  height: 40px;
  background: var(--primary);
  color: white;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.2rem;
  margin-bottom: var(--space-2);
}

.step-card h3 {
  margin-bottom: var(--space-1);
  font-size: 1rem;
  color: var(--text);
}

.step-card p {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0;
}

/* Quick Reference */
.quick-reference {
  margin-bottom: var(--space-4);
}

.quick-reference h2 {
  margin-bottom: var(--space-3);
  color: var(--text);
}

.reference-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-2);
}

.reference-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-2);
}

.reference-card h4 {
  margin: 0 0 var(--space-1);
  font-size: 0.85rem;
  color: var(--muted);
}

.reference-card code {
  background: var(--bg);
  padding: 4px 8px;
  border-radius: 6px;
  font-size: 0.8rem;
  word-break: break-all;
  display: block;
}

/* Scenarios Sections */
.scenarios-section {
  margin-bottom: var(--space-4);
}

.scenarios-section h2 {
  margin-bottom: var(--space-1);
  color: var(--text);
}

.section-desc {
  color: var(--muted);
  margin-bottom: var(--space-3);
}

.scenario-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--space-3);
}

.scenario-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-3);
  transition: box-shadow 0.2s, transform 0.2s;
}

.scenario-card:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  transform: translateY(-2px);
}

.scenario-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-2);
}

.scenario-number {
  font-weight: 700;
  color: var(--primary);
  font-size: 0.85rem;
}

.difficulty-badge {
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
}

.difficulty-badge.easy {
  background: var(--success-light);
  color: var(--success);
}

.difficulty-badge.medium {
  background: var(--warning-light);
  color: var(--warning);
}

.difficulty-badge.hard {
  background: var(--danger-light);
  color: var(--danger);
}

.scenario-card h3 {
  margin: 0 0 var(--space-1);
  font-size: 1.05rem;
  color: var(--text);
}

.scenario-desc {
  color: var(--muted);
  font-size: 0.9rem;
  margin-bottom: var(--space-2);
}

.scenario-details {
  background: var(--bg);
  border-radius: 8px;
  padding: var(--space-2);
  font-size: 0.85rem;
}

.scenario-details h4 {
  margin: 0 0 var(--space-1);
  font-size: 0.8rem;
  color: var(--muted);
  text-transform: uppercase;
}

.scenario-details ul {
  margin: 0 0 var(--space-2);
  padding-left: 18px;
}

.scenario-details li {
  margin-bottom: 4px;
  color: var(--text);
}

.scenario-details code {
  background: var(--panel);
  padding: 3px 6px;
  border-radius: 4px;
  font-size: 0.8rem;
  color: var(--primary);
}

/* Scenario Links */
.scenario-link {
  color: var(--primary);
  text-decoration: underline;
  text-decoration-style: dotted;
  text-underline-offset: 2px;
  transition: color 0.15s, text-decoration-color 0.15s;
}

.scenario-link:hover {
  color: var(--focus);
  text-decoration-style: solid;
}

/* Code Examples */
.code-examples {
  margin-bottom: var(--space-4);
}

.code-examples h2 {
  margin-bottom: var(--space-3);
  color: var(--text);
}

.code-tabs {
  display: flex;
  gap: var(--space-1);
  margin-bottom: var(--space-2);
}

.code-tab {
  padding: 8px 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px 8px 0 0;
  cursor: pointer;
  font-weight: 500;
  color: var(--muted);
  transition: all 0.2s;
}

.code-tab.active {
  background: var(--panel);
  color: var(--primary);
  border-bottom-color: var(--panel);
}

.code-content {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 0 var(--radius) var(--radius) var(--radius);
  overflow: hidden;
}

.code-content.hidden {
  display: none;
}

.code-content pre {
  margin: 0;
  padding: var(--space-3);
  overflow-x: auto;
}

.code-content code {
  font-family: 'Consolas', 'Monaco', monospace;
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--text);
}

/* Navigation Cards */
.nav-cards {
  margin-bottom: var(--space-4);
}

.nav-cards h2 {
  margin-bottom: var(--space-3);
  color: var(--text);
}

.nav-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--space-2);
}

.nav-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-3);
  text-decoration: none;
  text-align: center;
  transition: all 0.2s;
}

.nav-card:hover {
  border-color: var(--primary);
  background: var(--primary-light);
  transform: translateY(-2px);
}

.nav-icon {
  font-size: 2rem;
  display: block;
  margin-bottom: var(--space-1);
}

.nav-card h3 {
  margin: 0 0 4px;
  font-size: 0.95rem;
  color: var(--text);
}

.nav-card p {
  margin: 0;
  font-size: 0.8rem;
  color: var(--muted);
}

/* API Scenarios Section Color */
.api-scenarios .scenario-card {
  border-left: 4px solid var(--primary);
}

/* UI Scenarios Section Color */
.ui-scenarios .scenario-card {
  border-left: 4px solid var(--success);
}

/* Mixed Scenarios Section Color */
.mixed-scenarios .scenario-card {
  border-left: 4px solid var(--warning);
}