:root {
  --bg-canvas: #0d2a33;
  --bg-surface: #133a46;
  --bg-surface-hover: #1a4957;
  --bg-surface-alt: #091e25;
  --text-primary: #e0f2f1;
  --text-muted: #9bb3b8;
  --accent-primary: #ff6f59;
  --accent-secondary: #f59e0b;
  --border-subtle: #24505e;
  --border-strong: #387285;
  --pill-bg: #1e4f5e;
  --radius-sm: 2px;
  --radius-pill: 9999px;
  --ease-kinetic: cubic-bezier(0.16, 1, 0.3, 1);
  --shadow-elevation: 0 16px 36px -8px rgba(0, 0, 0, 0.45);
  --glow-accent: 0 0 20px -2px rgba(255, 111, 89, 0.35);
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg-canvas);
  color: var(--text-primary);
}

body {
  font-family: var(--font-family);
  background-color: var(--bg-canvas);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-wrap: anywhere;
  hyphens: auto;
}

/* Structural Shell with Hairline Boundary */
.site-frame {
  max-width: 1240px;
  width: 94%;
  margin: 1.5rem auto;
  border: 1px solid var(--border-subtle);
  background: var(--bg-canvas);
  position: relative;
  box-shadow: var(--shadow-elevation);
}

/* Header & Left Brand */
.site-header {
  position: relative;
  background: transparent;
  border-bottom: 1px solid var(--border-subtle);
  padding: 1.25rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-wrapper {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
}

.brand-symbol {
  width: 28px;
  height: 28px;
  background: var(--accent-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--bg-canvas);
  font-weight: 800;
  font-size: 0.9rem;
  border-radius: var(--radius-sm);
}

.brand-text {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  color: var(--text-primary);
  text-transform: lowercase;
}

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

/* Nav Menu */
.main-nav {
  display: flex;
  align-items: center;
  gap: 1.75rem;
}

.nav-links {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav-links a {
  color: var(--text-primary);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  position: relative;
  padding-bottom: 4px;
  transition: color 0.2s var(--ease-kinetic);
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent-primary);
  transition: width 0.25s var(--ease-kinetic);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent-primary);
}

.nav-cta {
  display: inline-block;
  background: var(--accent-primary);
  color: #0d2a33;
  padding: 0.55rem 1.15rem;
  font-size: 0.85rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: transform 0.2s var(--ease-kinetic), box-shadow 0.2s var(--ease-kinetic);
}

.nav-cta:hover {
  transform: translateY(-2px);
  box-shadow: var(--glow-accent);
}

/* Mobile Toggle */
.menu-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-size: 1.25rem;
  width: 40px;
  height: 40px;
  cursor: pointer;
  border-radius: var(--radius-sm);
  line-height: 1;
}

.mobile-overlay {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: var(--bg-surface);
  border-bottom: 2px solid var(--accent-primary);
  padding: 1.5rem 2rem;
  z-index: 999;
}

.mobile-overlay.is-active {
  display: block;
}

.mobile-overlay ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.mobile-overlay a {
  color: var(--text-primary);
  text-decoration: none;
  font-size: 1.05rem;
  font-weight: 700;
}

/* Typography & Layout Fundamentals */
.content-wrapper {
  padding: 3rem 2.5rem;
}

h1, h2, h3, h4 {
  color: var(--text-primary);
  letter-spacing: -0.035em;
  font-weight: 800;
  line-height: 1.15;
}

h1 {
  font-size: clamp(2.2rem, 5vw, 3.8rem);
  margin-bottom: 1.25rem;
}

h2 {
  font-size: clamp(1.6rem, 3.5vw, 2.3rem);
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-subtle);
}

h3 {
  font-size: 1.3rem;
  margin-bottom: 0.5rem;
}

p {
  margin-bottom: 1.25rem;
  color: var(--text-muted);
  font-size: 1.05rem;
}

.lead-copy {
  font-size: 1.25rem;
  color: var(--text-primary);
  max-width: 68ch;
  line-height: 1.5;
  margin-bottom: 2rem;
}

.prose {
  max-width: 72ch;
  margin: 0 auto;
}

.prose p {
  color: var(--text-muted);
  line-height: 1.7;
  font-size: 1.02rem;
}

/* Hero Section */
.hero-petrol {
  padding: 4rem 2rem 3rem 2rem;
  border-bottom: 1px solid var(--border-subtle);
  background: linear-gradient(180deg, rgba(19, 58, 70, 0.4) 0%, rgba(13, 42, 51, 0.8) 100%);
}

.hero-tag {
  display: inline-block;
  background: var(--pill-bg);
  color: var(--text-primary);
  border: 1px solid var(--border-strong);
  padding: 0.35rem 0.9rem;
  border-radius: var(--radius-pill);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 1.5rem;
}

.hero-actions {
  display: flex;
  gap: 1.25rem;
  align-items: center;
  flex-wrap: wrap;
  margin-top: 2rem;
}

.hero-secondary-link {
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 700;
  font-size: 0.95rem;
  position: relative;
  padding: 0.55rem 0;
}

.hero-secondary-link::after {
  content: " →";
  transition: transform 0.2s var(--ease-kinetic);
  display: inline-block;
}

.hero-secondary-link:hover::after {
  transform: translateX(4px);
  color: var(--accent-primary);
}

/* Metric Stat Strip */
.stat-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  border-bottom: 1px solid var(--border-subtle);
  background: var(--bg-surface-alt);
}

.stat-item {
  padding: 1.75rem 2rem;
  border-right: 1px solid var(--border-subtle);
}

.stat-item:last-child {
  border-right: none;
}

.stat-value {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--accent-primary);
  line-height: 1;
  margin-bottom: 0.35rem;
  font-variant-numeric: tabular-nums;
}

.stat-label {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

/* Dense Horizontal List Rows (No standard cards) */
.dense-list-section {
  padding: 3rem 2rem;
  border-bottom: 1px solid var(--border-subtle);
}

.section-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 1.75rem;
}

.horizontal-list {
  display: flex;
  flex-direction: column;
}

.list-row {
  display: grid;
  grid-template-columns: 80px 1.5fr 2fr 160px;
  align-items: center;
  padding: 1.35rem 1.25rem;
  border-top: 1px solid var(--border-subtle);
  background: transparent;
  transition: background-color 0.2s var(--ease-kinetic);
}

.list-row:last-child {
  border-bottom: 1px solid var(--border-subtle);
}

.list-row:hover {
  background: var(--bg-surface);
}

.row-index {
  font-family: monospace;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--accent-primary);
}

.row-title {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
}

.row-desc {
  color: var(--text-muted);
  font-size: 0.95rem;
  padding-right: 1.5rem;
  margin-bottom: 0;
}

.row-action {
  text-align: right;
}

.row-tag {
  display: inline-block;
  background: var(--pill-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-size: 0.75rem;
  padding: 0.2rem 0.65rem;
  border-radius: var(--radius-pill);
  font-weight: 600;
}

/* Split Image Showcase */
.media-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  align-items: center;
  padding: 3rem 2rem;
  border-bottom: 1px solid var(--border-subtle);
}

.media-viewport {
  width: 100%;
  aspect-ratio: 16 / 10;
  border: 1px solid var(--border-subtle);
  background: var(--bg-surface-alt);
  position: relative;
}

.media-viewport img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  filter: contrast(105%) brightness(95%);
}

.media-caption {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
  font-family: monospace;
}

/* Interactive Tabs & Accordions */
.tab-container {
  margin: 2rem 0;
}

.tab-nav {
  display: flex;
  gap: 0.5rem;
  border-bottom: 1px solid var(--border-subtle);
  margin-bottom: 1.5rem;
}

.tab-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 700;
  padding: 0.75rem 1.25rem;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all 0.2s var(--ease-kinetic);
}

.tab-btn.active {
  color: var(--accent-primary);
  border-bottom-color: var(--accent-primary);
  background: rgba(255, 111, 89, 0.05);
}

.tab-pane {
  display: none;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  padding: 2rem;
}

.tab-pane.active {
  display: block;
}

/* Accordion Component */
.accordion {
  border-top: 1px solid var(--border-subtle);
  margin-top: 1.5rem;
}

.accordion-item {
  border-bottom: 1px solid var(--border-subtle);
}

.accordion-header {
  width: 100%;
  background: transparent;
  border: none;
  padding: 1.25rem 0.5rem;
  text-align: left;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text-primary);
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
}

.accordion-header:hover {
  color: var(--accent-primary);
}

.accordion-icon {
  font-size: 1.2rem;
  color: var(--accent-primary);
  transition: transform 0.2s var(--ease-kinetic);
}

.accordion-content {
  display: none;
  padding: 0 0.5rem 1.25rem 0.5rem;
  color: var(--text-muted);
}

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

.accordion-item.open .accordion-icon {
  transform: rotate(45deg);
}

/* Study Planner Constructor Tool */
.tool-box {
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  padding: 2rem;
  margin: 2.5rem 0;
}

.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  margin-bottom: 1.5rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.form-group label {
  font-size: 0.85rem;
  text-transform: uppercase;
  font-weight: 700;
  letter-spacing: 0.05em;
}

.form-group input,
.form-group select,
.form-group textarea {
  background: var(--bg-canvas);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  padding: 0.75rem 1rem;
  font-size: 0.95rem;
  font-family: inherit;
  border-radius: var(--radius-sm);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 2px rgba(255, 111, 89, 0.2);
}

.tool-buttons {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}

.tool-output {
  margin-top: 1.5rem;
  background: var(--bg-surface-alt);
  border: 1px dashed var(--border-strong);
  padding: 1.25rem;
  font-family: monospace;
  font-size: 0.9rem;
  white-space: pre-wrap;
  color: var(--text-primary);
  min-height: 120px;
}

/* Grid & Masonry Panels */
.panel-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.panel-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.panel-card h3 {
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 0.75rem;
  margin-bottom: 1rem;
}

/* Data Tables */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  margin: 2rem 0;
  border: 1px solid var(--border-subtle);
}

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

th, td {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
}

th {
  background: var(--bg-surface-alt);
  color: var(--text-primary);
  font-weight: 700;
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.05em;
}

tr:hover td {
  background: var(--bg-surface);
}

/* Footer Specification */
.site-footer {
  border-top: 1px solid var(--border-subtle);
  background: var(--bg-surface-alt);
  padding: 3.5rem 2rem 2rem 2rem;
  margin-top: auto;
}

.footer-inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 2.5rem;
  margin-bottom: 2.5rem;
}

.footer-brand-title {
  font-size: 1.2rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
}

.footer-col h4 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.2s ease;
}

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

.footer-meta {
  border-top: 1px solid var(--border-subtle);
  padding-top: 1.75rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-domain-link {
  color: var(--accent-primary);
  text-decoration: none;
  font-weight: 700;
}

/* Responsive adjustments */
@media (max-width: 900px) {
  .list-row {
    grid-template-columns: 40px 1fr;
    gap: 0.5rem;
  }
  .row-desc {
    grid-column: 2 / -1;
    padding-right: 0;
  }
  .row-action {
    grid-column: 2 / -1;
    text-align: left;
    margin-top: 0.5rem;
  }
  .media-split {
    grid-template-columns: 1fr;
  }
  .footer-inner {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .main-nav .nav-links,
  .main-nav .nav-cta {
    display: none;
  }
  .menu-toggle {
    display: block;
  }
  .site-header {
    padding: 1rem 1.25rem;
  }
  .content-wrapper {
    padding: 2rem 1.25rem;
  }
  .form-grid {
    grid-template-columns: 1fr;
  }
  .footer-inner {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce){*,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important;scroll-behavior:auto!important}}