/* ==========================================================================
   TubeCraft AI — Core Design System & Global Styles
   ========================================================================== */

:root {
  /* Color System */
  --bg-dark: #0B0F17;
  --bg-darker: #06090E;
  --surface-dark: #131B2A;
  --surface-card: #1B2538;
  --surface-card-hover: #223048;
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-card: #2D3B55;
  --border-focus: #6366F1;

  /* Brand Accents */
  --brand-red: #FF0033;
  --brand-red-hover: #E6002E;
  --accent-indigo: #6366F1;
  --accent-cyan: #00F2FE;
  --accent-emerald: #10B981;
  --accent-amber: #F59E0B;
  --accent-purple: #8B5CF6;

  /* Typography Colors */
  --text-primary: #F8FAFC;
  --text-secondary: #94A3B8;
  --text-muted: #64748B;
  --text-on-accent: #FFFFFF;

  /* Elevation & Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.6);
  --shadow-glow-red: 0 0 30px rgba(255, 0, 51, 0.35);
  --shadow-glow-cyan: 0 0 30px rgba(0, 242, 254, 0.3);

  /* Dimensions & Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-pill: 9999px;
  --container-max: 1280px;
  --header-height: 70px;
}

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

html {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-primary);
  line-height: 1.6;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-dark);
  color: var(--text-primary);
  overflow-x: hidden;
}

/* Typography Hierarchy */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2rem, 4vw, 3rem); font-weight: 800; }
h2 { font-size: clamp(1.6rem, 3vw, 2.25rem); }
h3 { font-size: clamp(1.25rem, 2vw, 1.5rem); }
h4 { font-size: 1.15rem; }

p {
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 1.65;
}

a {
  color: var(--accent-cyan);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: #38bdf8;
}

code, pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

/* Container */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 20px;
  padding-right: 20px;
}

/* Header & Navigation */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  background: rgba(11, 15, 23, 0.88);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-subtle);
}

.site-header .container {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-link {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-primary);
}

.logo-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  background: linear-gradient(135deg, var(--brand-red) 0%, #B91C1C 100%);
  border-radius: var(--radius-md);
  box-shadow: 0 0 16px rgba(255, 0, 51, 0.4);
  color: #FFF;
}

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

.logo-title {
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: #FFF;
  display: flex;
  align-items: center;
  gap: 4px;
}

.logo-title .ai-chip {
  font-size: 0.65rem;
  font-weight: 700;
  background: var(--accent-indigo);
  color: #FFF;
  padding: 2px 6px;
  border-radius: 4px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.logo-sub {
  font-size: 0.72rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* Navigation Links - Clean Top-Right Menu */
.main-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
}

.nav-link {
  color: var(--text-secondary);
  font-size: 0.92rem;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.18s ease;
  position: relative;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.nav-link:hover {
  color: #FFF;
  background: rgba(255, 255, 255, 0.06);
}

.nav-link.active {
  color: #FFF;
  background: rgba(255, 255, 255, 0.09);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 12px;
  right: 12px;
  height: 2px;
  background: var(--brand-red);
  border-radius: 2px;
}

.nav-link .nav-pill-badge {
  font-size: 0.65rem;
  font-weight: 700;
  padding: 2px 6px;
  border-radius: 9999px;
  background: rgba(255, 0, 51, 0.18);
  color: #FF5A79;
  border: 1px solid rgba(255, 0, 51, 0.35);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.nav-cta-group {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-left: 8px;
}

/* Mobile Toggle */
.mobile-menu-btn {
  display: none;
  background: transparent;
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  align-items: center;
  justify-content: center;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.2s ease;
  border: 1px solid transparent;
  white-space: nowrap;
}

.btn-primary {
  background: var(--brand-red);
  color: #FFF;
  box-shadow: 0 4px 14px rgba(255, 0, 51, 0.35);
}

.btn-primary:hover {
  background: var(--brand-red-hover);
  color: #FFF;
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(255, 0, 51, 0.45);
}

.btn-secondary {
  background: var(--surface-card);
  color: var(--text-primary);
  border-color: var(--border-card);
}

.btn-secondary:hover {
  background: var(--surface-card-hover);
  border-color: rgba(255, 255, 255, 0.2);
  color: #FFF;
}

.btn-accent {
  background: linear-gradient(135deg, var(--accent-indigo) 0%, #4F46E5 100%);
  color: #FFF;
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.35);
}

.btn-accent:hover {
  background: linear-gradient(135deg, #4F46E5 0%, #4338CA 100%);
  color: #FFF;
  transform: translateY(-1px);
}

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

.btn-outline:hover {
  border-color: var(--text-primary);
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.04);
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.82rem;
  border-radius: var(--radius-sm);
}

.btn-lg {
  padding: 14px 28px;
  font-size: 1.05rem;
  border-radius: var(--radius-md);
}

/* Badge Chips */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.badge-red { background: rgba(255, 0, 51, 0.15); color: #FF4D6D; border: 1px solid rgba(255, 0, 51, 0.3); }
.badge-indigo { background: rgba(99, 102, 241, 0.15); color: #818CF8; border: 1px solid rgba(99, 102, 241, 0.3); }
.badge-emerald { background: rgba(16, 185, 129, 0.15); color: #34D399; border: 1px solid rgba(16, 185, 129, 0.3); }
.badge-amber { background: rgba(245, 158, 11, 0.15); color: #FBBF24; border: 1px solid rgba(245, 158, 11, 0.3); }
.badge-cyan { background: rgba(0, 242, 254, 0.15); color: #38BDF8; border: 1px solid rgba(0, 242, 254, 0.3); }

/* Breadcrumbs */
.breadcrumb-nav {
  padding: 16px 0;
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.breadcrumb-nav a {
  color: var(--text-secondary);
}

.breadcrumb-nav a:hover {
  color: var(--text-primary);
}

.breadcrumb-separator {
  color: var(--border-card);
}

/* Section Header Styles */
.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 48px auto;
}

.section-header .badge {
  margin-bottom: 12px;
}

.section-header h2 {
  margin-bottom: 14px;
}

.section-header p {
  font-size: 1.05rem;
  color: var(--text-secondary);
}

/* Content Cards */
.card {
  background: var(--surface-dark);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  border-color: rgba(255, 255, 255, 0.15);
  box-shadow: var(--shadow-md);
}

/* Educational Prose Styling */
.editorial-prose {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.75;
}

.editorial-prose h2 {
  color: var(--text-primary);
  margin-top: 48px;
  margin-bottom: 18px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-subtle);
}

.editorial-prose h3 {
  color: var(--text-primary);
  margin-top: 32px;
  margin-bottom: 14px;
}

.editorial-prose p {
  margin-bottom: 18px;
}

.editorial-prose ul, .editorial-prose ol {
  margin-bottom: 24px;
  padding-left: 28px;
}

.editorial-prose li {
  margin-bottom: 8px;
}

.editorial-prose strong {
  color: var(--text-primary);
}

.editorial-prose blockquote {
  border-left: 4px solid var(--brand-red);
  background: var(--surface-dark);
  padding: 16px 20px;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  margin: 24px 0;
  font-style: italic;
  color: var(--text-primary);
}

/* Data Table */
.data-table-container {
  overflow-x: auto;
  margin: 28px 0;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.95rem;
}

.data-table th {
  background: var(--surface-card);
  color: var(--text-primary);
  padding: 12px 16px;
  font-weight: 700;
  border-bottom: 1px solid var(--border-card);
}

.data-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

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

.data-table tr:hover td {
  background: rgba(255, 255, 255, 0.02);
}

/* Accordion Component */
.accordion {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.accordion-item {
  background: var(--surface-dark);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color 0.2s ease;
}

.accordion-item.active {
  border-color: var(--border-card);
}

.accordion-trigger {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 20px;
  background: transparent;
  border: none;
  color: var(--text-primary);
  font-size: 1.05rem;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
  transition: background 0.15s ease;
}

.accordion-trigger:hover {
  background: rgba(255, 255, 255, 0.02);
}

.accordion-icon {
  display: inline-flex;
  transition: transform 0.2s ease;
  color: var(--text-muted);
}

.accordion-item.active .accordion-icon {
  transform: rotate(180deg);
  color: var(--brand-red);
}

.accordion-content {
  display: none;
  padding: 0 20px 20px 20px;
  color: var(--text-secondary);
  font-size: 0.98rem;
  line-height: 1.65;
}

.accordion-item.active .accordion-content {
  display: block;
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 10px;
  pointer-events: none;
}

.toast {
  pointer-events: auto;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 18px;
  background: var(--surface-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  color: #FFF;
  font-size: 0.9rem;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  animation: toastSlideIn 0.25s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.toast.toast-success { border-color: var(--accent-emerald); }
.toast.toast-error { border-color: var(--brand-red); }
.toast.toast-warning { border-color: var(--accent-amber); }

@keyframes toastSlideIn {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Footer */
.site-footer {
  background: var(--bg-darker);
  border-top: 1px solid var(--border-subtle);
  padding: 60px 0 30px 0;
  margin-top: auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 48px;
}

.footer-col-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 16px;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-links a {
  color: var(--text-secondary);
  font-size: 0.88rem;
  text-decoration: none;
  transition: color 0.15s ease;
}

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

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-disclaimer-note {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin-top: 12px;
}