/* ============================================================
   TERRAIN — Shared Design System
   Imports: Google Fonts (Playfair Display, IBM Plex Mono, Source Serif 4)
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:wght@400;500;600;700&family=IBM+Plex+Mono:wght@400;500;600;700&family=Source+Serif+4:ital,wght@0,300;0,400;0,600;1,400&display=swap');

/* ============================================================
   CSS CUSTOM PROPERTIES
   ============================================================ */

:root {
  /* --- Color System --- */
  --color-bg: #f7f4f0;
  --color-bg-card: #ffffff;
  --color-bg-subtle: #f0ece6;

  --color-text: #1a1a1a;
  --color-text-secondary: #666666;
  --color-text-muted: #999999;

  --color-border: #e0d8d0;
  --color-border-strong: #c8bfb5;

  --color-accent: #bd0026;
  --color-accent-hover: #8b0019;
  --color-accent-light: #fff1f1;

  /* Grade/tier pill colors */
  --color-tier-a: #bd0026;
  --color-tier-b: #fd8d3c;
  --color-tier-c: #fecc5c;
  --color-tier-a-text: #ffffff;
  --color-tier-b-text: #1a1a1a;
  --color-tier-c-text: #1a1a1a;

  /* Intervention type colors */
  --color-type-a: #1a1a1a;
  --color-type-b: #555555;
  --color-type-c: #999999;

  /* Banner accent colors */
  --color-banner-info-bg: #eff6ff;
  --color-banner-info-border: #3b82f6;
  --color-banner-warning-bg: #fffbeb;
  --color-banner-warning-border: #f59e0b;
  --color-banner-muted-bg: #f5f5f5;
  --color-banner-muted-border: #9ca3af;

  /* --- Typography --- */
  --font-serif: 'Playfair Display', Georgia, serif;
  --font-mono: 'IBM Plex Mono', 'Courier New', monospace;
  --font-body: 'Source Serif 4', Georgia, serif;

  /* --- Type Scale --- */
  --text-xs: 11px;
  --text-sm: 13px;
  --text-base: 16px;
  --text-lg: 20px;
  --text-xl: 28px;
  --text-2xl: 38px;

  /* --- Spacing --- */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  /* --- Radius --- */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* --- Shadows --- */
  --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-card-hover: 0 4px 16px rgba(0, 0, 0, 0.10);
  --shadow-pill: 0 1px 2px rgba(0, 0, 0, 0.12);
  --shadow-nav: 0 1px 0 var(--color-border);

  /* --- Breakpoints (reference values, used in media queries below) --- */
  --breakpoint-mobile: 768px;
  --breakpoint-tablet: 1024px;

  /* --- Nav --- */
  --nav-height: 72px;
  --nav-height-mobile: 48px;
}

/* ============================================================
   BASE RESET & GLOBAL DEFAULTS
   ============================================================ */

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

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

body {
  background-color: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a:hover {
  text-decoration: underline;
}

img, svg {
  display: block;
  max-width: 100%;
}

/* ============================================================
   1. NAVIGATION BAR (.terrain-nav)
   ============================================================ */

.terrain-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  width: 100%;
  height: var(--nav-height);
  background-color: var(--color-bg-card);
  border-bottom: 1px solid var(--color-border);
  box-shadow: none;
  display: flex;
  align-items: center;
}

.terrain-nav__inner {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

/* Wordmark */
.terrain-nav__brand {
  font-family: var(--font-mono);
  font-size: 42px;
  font-weight: 700;
  letter-spacing: 3.5px;
  text-transform: uppercase;
  color: var(--color-text);
  text-decoration: none;
  flex-shrink: 0;
  line-height: 1;
}

.terrain-nav__brand:hover {
  color: var(--color-accent);
  text-decoration: none;
}

/* Desktop nav links */
.terrain-nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  list-style: none;
}

.terrain-nav__links a {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
  transition: color 150ms ease, border-color 150ms ease;
}

.terrain-nav__links a:hover {
  color: var(--color-accent);
  text-decoration: none;
  border-bottom-color: transparent;
}

/* Active nav link */
.terrain-nav__links a.active,
.terrain-nav__links a[aria-current="page"] {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* External link */
.terrain-nav__links a[target="_blank"]::after {
  content: ' ↗';
  font-size: 10px;
  opacity: 0.7;
}

/* Hamburger button (mobile only) */
.terrain-nav__hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
  color: var(--color-text);
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  min-width: 44px;
  min-height: 44px;
}

.terrain-nav__hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 1px;
  transition: transform 200ms ease, opacity 200ms ease;
}

/* Mobile drawer */
.terrain-nav__drawer {
  display: none;
  position: absolute;
  top: var(--nav-height-mobile);
  left: 0;
  right: 0;
  background-color: var(--color-bg-card);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-4) var(--space-6);
  z-index: 99;
}

.terrain-nav__drawer.open {
  display: block;
}

.terrain-nav__drawer ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.terrain-nav__drawer a {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 1px;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--space-3) 0;
  border-bottom: 1px solid var(--color-border);
  min-height: 44px;
  display: flex;
  align-items: center;
  transition: color 150ms ease;
}

.terrain-nav__drawer a:hover,
.terrain-nav__drawer a.active {
  color: var(--color-accent);
  text-decoration: none;
}

.terrain-nav__drawer li:last-child a {
  border-bottom: none;
}

@media (max-width: 768px) {
  .terrain-nav {
    height: var(--nav-height-mobile);
    position: relative; /* allow drawer to position relative to nav */
  }

  .terrain-nav__links {
    display: none;
  }

  .terrain-nav__hamburger {
    display: flex;
  }

  .terrain-nav__inner {
    padding: 0 var(--space-4);
  }
}

/* ============================================================
   2. GRADE / TIER PILLS (.grade-pill)
   ============================================================ */

.grade-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  border-radius: var(--radius-sm);
  padding: 2px 8px;
  line-height: 1.4;
  box-shadow: var(--shadow-pill);
  white-space: nowrap;
}

/* Grade tiers */
.grade-pill.tier-a {
  background-color: var(--color-tier-a);
  color: var(--color-tier-a-text);
}

.grade-pill.tier-b {
  background-color: var(--color-tier-b);
  color: var(--color-tier-b-text);
}

.grade-pill.tier-c {
  background-color: var(--color-tier-c);
  color: var(--color-tier-c-text);
}

/* Intervention types */
.grade-pill.type-a {
  background-color: var(--color-type-a);
  color: #ffffff;
}

.grade-pill.type-b {
  background-color: var(--color-type-b);
  color: #ffffff;
}

.grade-pill.type-c {
  background-color: #e5e5e5;
  color: var(--color-text-secondary);
  box-shadow: none;
}

/* ============================================================
   3. PROGRESS DOTS (.progress-dots)
   ============================================================ */

.progress-dots {
  display: flex;
  align-items: center;
  gap: 12px;
}

.progress-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--color-border-strong);
  flex-shrink: 0;
  transition: background-color 200ms ease, width 200ms ease, height 200ms ease;
}

.progress-dot.active {
  width: 10px;
  height: 10px;
  background-color: var(--color-accent);
}

.progress-dot.complete {
  width: 8px;
  height: 8px;
  background-color: var(--color-accent);
}

/* ============================================================
   4. CARDS (.terrain-card)
   ============================================================ */

.terrain-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-6);
  box-shadow: var(--shadow-card);
  transition: box-shadow 180ms ease, border-color 180ms ease;
}

.terrain-card.clickable {
  cursor: pointer;
}

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

.terrain-card.featured {
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.09);
  border-left: 3px solid var(--color-accent);
}

.terrain-card.featured:hover {
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.12);
}

/* ============================================================
   5. STAT BLOCKS (.stat-block)
   ============================================================ */

.stat-block {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.stat-block__number {
  font-family: var(--font-serif);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1;
}

.stat-block__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--color-text-muted);
  line-height: 1.3;
}

/* ============================================================
   6. SECTION HEADERS
   ============================================================ */

.section-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--color-text-muted);
  display: block;
  margin-bottom: var(--space-2);
}

.section-title {
  font-family: var(--font-serif);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.25;
  margin-bottom: var(--space-3);
}

.section-subtitle {
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text-secondary);
  line-height: 1.65;
  max-width: 58ch;
}

/* ============================================================
   7. BUTTONS (.btn-*)
   ============================================================ */

.btn-primary,
.btn-secondary,
.btn-ghost {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: 0.5px;
  border-radius: var(--radius-md);
  padding: 10px 20px;
  cursor: pointer;
  text-decoration: none;
  border: 1px solid transparent;
  transition: background-color 150ms ease, color 150ms ease,
              border-color 150ms ease, box-shadow 150ms ease,
              transform 80ms ease;
  min-height: 40px;
  white-space: nowrap;
  line-height: 1;
}

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

.btn-primary:hover {
  background-color: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
  text-decoration: none;
  color: #ffffff;
}

.btn-primary:active {
  transform: translateY(1px);
  box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.15);
}

/* Secondary */
.btn-secondary {
  background-color: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.btn-secondary:hover {
  background-color: var(--color-accent-light);
  text-decoration: none;
  color: var(--color-accent);
}

.btn-secondary:active {
  transform: translateY(1px);
}

/* Ghost */
.btn-ghost {
  background-color: transparent;
  color: var(--color-text-secondary);
  border-color: transparent;
  padding-left: var(--space-2);
  padding-right: var(--space-2);
}

.btn-ghost:hover {
  color: var(--color-text);
  text-decoration: underline;
}

/* ============================================================
   8. DIVIDER WITH LABEL (.divider-label)
   ============================================================ */

.divider-label {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  margin: var(--space-6) 0;
}

.divider-label::before,
.divider-label::after {
  content: '';
  flex: 1;
  height: 1px;
  background-color: var(--color-border);
}

.divider-label__text {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--color-text-muted);
  white-space: nowrap;
  background-color: inherit;
  padding: 0 var(--space-2);
}

/* ============================================================
   9. BANNERS / CALLOUTS (.terrain-banner)
   ============================================================ */

.terrain-banner {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  padding: 12px 20px;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  line-height: 1.55;
  border-radius: var(--radius-sm);
  border-left: 3px solid;
}

.terrain-banner p {
  margin: 0;
  color: var(--color-text-secondary);
}

.terrain-banner strong {
  color: var(--color-text);
}

/* Info */
.terrain-banner.info {
  background-color: var(--color-banner-info-bg);
  border-left-color: var(--color-banner-info-border);
}

/* Warning */
.terrain-banner.warning {
  background-color: var(--color-banner-warning-bg);
  border-left-color: var(--color-banner-warning-border);
}

/* Muted */
.terrain-banner.muted {
  background-color: var(--color-banner-muted-bg);
  border-left-color: var(--color-banner-muted-border);
}

/* ============================================================
   UTILITY CLASSES
   ============================================================ */

.container {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.container--narrow {
  max-width: 780px;
}

.stack {
  display: flex;
  flex-direction: column;
}

.stack--4 { gap: var(--space-4); }
.stack--6 { gap: var(--space-6); }
.stack--8 { gap: var(--space-8); }

.row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
}

.row--gap-4 { gap: var(--space-4); }
.row--gap-6 { gap: var(--space-6); }

.text-mono {
  font-family: var(--font-mono);
}

.text-serif {
  font-family: var(--font-serif);
}

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

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

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* ============================================================
   RESPONSIVE — MOBILE (≤768px)
   ============================================================ */

@media (max-width: 768px) {
  :root {
    --text-xl: 24px;
    --text-2xl: 30px;
  }

  .terrain-card {
    padding: var(--space-4);
  }

  .section-title {
    font-size: 22px;
  }

  .stat-block__number {
    font-size: 28px;
  }

  .container {
    padding: 0 var(--space-4);
  }

  /* Full-width cards on mobile */
  .terrain-card--auto-full {
    width: 100%;
  }
}

/* ============================================================
   RESPONSIVE — TABLET (769px–1024px)
   ============================================================ */

@media (min-width: 769px) and (max-width: 1024px) {
  .container {
    padding: 0 var(--space-5);
  }
}