/* ============================================================
   Lighthouse Philosophy — Stylesheet
   Design system applied from Stitch style guide (April 2026).

   Color palette:
     Primary   #2B4C5B  — dark teal (nav, headings, primary buttons)
     Secondary #E65A4B  — coral red (CTA, accent, links, progress bar)
     Tertiary  #F08C4A  — orange (series labels, secondary highlights)
     Neutral   #F2F4F5  — light gray (page bg, card surfaces)

   Typography:
     Heading: Libre Baskerville (Baskerville, serif)
     Body:    Manrope (sans-serif)
   ============================================================ */

/* ── CSS Custom Properties ── */
:root {
  /* Brand Colors */
  --color-primary:          #2B4C5B;
  --color-primary-dark:     #1e3642;
  --color-primary-light:    #3d6478;
  --color-secondary:        #E65A4B;
  --color-secondary-dark:   #c94437;
  --color-secondary-light:  #eb7a6e;
  --color-tertiary:         #F08C4A;
  --color-tertiary-dark:    #d4762e;
  --color-neutral:          #F2F4F5;

  /* Semantic Color Tokens (light theme) */
  --color-bg:               #ffffff;
  --color-bg-alt:           #F2F4F5;
  --color-surface:          #F2F4F5;
  --color-surface-raised:   #ffffff;
  --color-nav-bg:           #2B4C5B;
  --color-nav-text:         #ffffff;
  --color-text:             #2a2a2a;
  --color-heading:          #2B4C5B;
  --color-muted:            #5f6b74;
  --color-border:           #dde2e6;

  /* Accent (main interactive color = Secondary/coral) */
  --color-accent:           #E65A4B;
  --color-accent-hover:     #c94437;

  /* Series label color = Tertiary/orange */
  --color-series:           #F08C4A;

  /* Typography */
  --font-heading: 'Libre Baskerville', Baskerville, 'Baskerville Old Face', Georgia, serif;
  --font-body:    'Manrope', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  /* Layout */
  --max-width:        1200px;
  --content-width:    720px;
  --reading-width:    65ch;

  /* Spacing */
  --space-xs:   0.25rem;
  --space-sm:   0.5rem;
  --space-md:   1rem;
  --space-lg:   2rem;
  --space-xl:   3rem;
  --space-2xl:  4rem;

  /* Misc */
  --radius:     8px;
  --transition: 200ms ease;

  /* Nav height (used for scroll offset) */
  --nav-height: 64px;
}

/* ── Dark Theme ── */
[data-theme="dark"] {
  --color-bg:               #111c22;
  --color-bg-alt:           #162028;
  --color-surface:          #1a2832;
  --color-surface-raised:   #1f3040;
  --color-nav-bg:           #0d1820;
  --color-nav-text:         #e8f0f4;
  --color-text:             #d4dfe6;
  --color-heading:          #a8cfe0;
  --color-muted:            #7a99aa;
  --color-border:           #253545;
  --color-accent:           #E65A4B;
  --color-accent-hover:     #eb7a6e;
  --color-series:           #F08C4A;
}

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

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

body {
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg-alt);
  transition: background-color var(--transition), color var(--transition);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: color var(--transition);
}

a:hover {
  color: var(--color-accent-hover);
}

a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: 2px;
}

/* ── Skip Link (accessibility) ── */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  padding: var(--space-sm) var(--space-md);
  background: var(--color-accent);
  color: #fff;
  border-radius: var(--radius);
  z-index: 9999;
  font-weight: 600;
  text-decoration: none;
}

.skip-link:focus {
  top: var(--space-md);
}

/* ── Container ── */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ── Reading Progress Bar ── */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  z-index: 1000;
  background: transparent;
}

.reading-progress__bar {
  height: 100%;
  width: 0%;
  background: var(--color-accent);
  transition: width 100ms linear;
}

/* ── Site Header ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-nav-bg);
  border-bottom: none;
  padding: var(--space-sm) 0;
  transition: background-color var(--transition);
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
}

.site-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
  color: var(--color-nav-text);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  flex-shrink: 0;
}

.site-logo img {
  width: 40px;
  height: 40px;
}

/* ── Navigation ── */
.site-nav {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.nav-toggle {
  display: flex;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
}

.nav-toggle__bar {
  width: 24px;
  height: 2px;
  background: var(--color-nav-text);
  transition: transform var(--transition), opacity var(--transition);
}

/* Hamburger → X animation */
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
  transform: rotate(45deg) translate(4px, 4px);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
  transform: rotate(-45deg) translate(4px, -4px);
}

.nav-menu {
  list-style: none;
  display: none;
  flex-direction: column;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: var(--color-primary);
  border-bottom: 3px solid var(--color-secondary);
  padding: var(--space-md);
  gap: var(--space-xs);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.nav-menu.is-open {
  display: flex;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-md);
  color: var(--color-nav-text);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
  opacity: 0.9;
}

.nav-link:hover {
  background: rgba(255,255,255,0.1);
  color: #ffffff;
  opacity: 1;
}

.nav-link--active {
  color: var(--color-secondary-light);
  opacity: 1;
  font-weight: 600;
}

.nav-chevron {
  transition: transform var(--transition);
}

.nav-dropdown {
  list-style: none;
  padding-left: var(--space-lg);
}

.nav-dropdown__link {
  display: block;
  padding: var(--space-xs) var(--space-md);
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.9rem;
  border-radius: var(--radius);
  transition: color var(--transition), background var(--transition);
}

.nav-dropdown__link:hover,
.nav-dropdown__link.nav-link--active {
  color: var(--color-accent);
  background: var(--color-surface);
}

/* ── Theme Toggle ── */
.theme-toggle {
  background: rgba(255,255,255,0.12);
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 50%;
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--color-nav-text);
  flex-shrink: 0;
  transition: background var(--transition), border-color var(--transition);
}

.theme-toggle:hover {
  background: rgba(255,255,255,0.22);
  border-color: rgba(255,255,255,0.5);
}

[data-theme="light"] .theme-toggle__icon--moon { display: none; }
[data-theme="dark"] .theme-toggle__icon--sun { display: none; }

/* ── Hero Section ── */
.hero {
  padding: var(--space-2xl) 0;
  text-align: center;
  background: linear-gradient(160deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: #fff;
  position: relative;
  overflow: hidden;
}

/* Subtle lighthouse beam sweep effect */
.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(ellipse at center, rgba(240,140,74,0.15) 0%, transparent 70%);
  pointer-events: none;
}

.hero__title {
  font-family: var(--font-heading);
  font-size: clamp(1.8rem, 5vw, 3rem);
  color: #ffffff;
  line-height: 1.2;
  margin-bottom: var(--space-md);
}

.hero__subtitle {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  color: rgba(255,255,255,0.8);
  max-width: 600px;
  margin: 0 auto var(--space-lg);
  line-height: 1.6;
}

.hero__cta {
  display: inline-block;
  padding: var(--space-sm) var(--space-lg);
  background: var(--color-accent);
  color: #fff;
  text-decoration: none;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 1rem;
  transition: background var(--transition), transform var(--transition);
}

.hero__cta:hover {
  background: var(--color-accent-hover);
  color: #fff;
  transform: translateY(-1px);
}

/* ── Sections ── */
.section {
  padding: var(--space-xl) 0;
}

.section__heading {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  color: var(--color-heading);
  margin-bottom: var(--space-sm);
}

.section__subheading {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  color: var(--color-heading);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
}

.section__intro {
  color: var(--color-muted);
  max-width: 600px;
  margin-bottom: var(--space-lg);
}

/* ── Card Grid ── */
.card-grid {
  display: grid;
  gap: var(--space-md);
  grid-template-columns: 1fr;
}

.card {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  padding: var(--space-lg);
  background: var(--color-surface-raised);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--color-text);
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
}

.card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(43,76,91,0.12);
  color: var(--color-text);
}

.card--featured {
  border-left: 4px solid var(--color-secondary);
}

.card__series {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--color-series);
}

.card__title {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  color: var(--color-heading);
  line-height: 1.3;
}

.card__excerpt {
  font-size: 0.95rem;
  color: var(--color-muted);
  line-height: 1.5;
}

/* ── Page Layout ── */
.page {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-md);
}

.page-header {
  margin-bottom: var(--space-xl);
}

.page-header__title {
  font-family: var(--font-heading);
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  color: var(--color-heading);
  line-height: 1.2;
  margin-bottom: var(--space-sm);
}

.page-header__subtitle {
  font-size: 1.1rem;
  color: var(--color-muted);
}

/* ── Article Layout ── */
.article {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-lg) var(--space-md);
}

/* Breadcrumbs */
.breadcrumb ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  font-size: 0.85rem;
  color: var(--color-muted);
  margin-bottom: var(--space-lg);
}

.breadcrumb li:not(:last-child)::after {
  content: " / ";
  margin-left: var(--space-xs);
  color: var(--color-border);
}

.breadcrumb a {
  color: var(--color-muted);
  text-decoration: none;
}

.breadcrumb a:hover {
  color: var(--color-accent);
}

.breadcrumb [aria-current] {
  color: var(--color-text);
  font-weight: 500;
}

/* Article Header */
.article-header {
  text-align: center;
  max-width: var(--content-width);
  margin: 0 auto var(--space-xl);
}

.article-header__series {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--color-series);
  margin-bottom: var(--space-sm);
}

.article-header__title {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 5vw, 2.75rem);
  color: var(--color-heading);
  line-height: 1.15;
  margin-bottom: var(--space-sm);
}

.article-header__subtitle {
  font-size: 1.15rem;
  color: var(--color-muted);
  margin-bottom: var(--space-md);
}

.article-header__meta {
  font-size: 0.85rem;
  color: var(--color-muted);
}

.article-header__separator {
  margin: 0 var(--space-sm);
}

/* Article Layout: TOC + Body */
.article-layout {
  display: flex;
  gap: var(--space-xl);
  max-width: calc(var(--content-width) + 280px);
  margin: 0 auto;
}

/* Table of Contents */
.toc {
  width: 250px;
  flex-shrink: 0;
  align-self: flex-start;
  position: sticky;
  top: 80px;
}

.toc__heading {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-heading);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-sm);
  cursor: pointer;
  list-style: none;
}

.toc__heading::-webkit-details-marker {
  display: none;
}

.toc__list {
  list-style: none;
}

.toc__item {
  margin-bottom: var(--space-xs);
}

.toc__item--h3 {
  padding-left: var(--space-md);
}

.toc__link {
  display: block;
  padding: 2px 0;
  font-size: 0.85rem;
  color: var(--color-muted);
  text-decoration: none;
  line-height: 1.4;
  border-left: 2px solid transparent;
  padding-left: var(--space-sm);
  transition: color var(--transition), border-color var(--transition);
}

.toc__link:hover,
.toc__link.is-active {
  color: var(--color-primary);
  border-left-color: var(--color-secondary);
}

/* Article Body: Prose Styles */
.article-body {
  flex: 1;
  min-width: 0;
  max-width: var(--reading-width);
}

.prose h2 {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  color: var(--color-heading);
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
  line-height: 1.25;
}

.prose h3 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  color: var(--color-heading);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-sm);
  line-height: 1.3;
}

.prose p {
  margin-bottom: var(--space-md);
  line-height: 1.75;
}

.prose ul,
.prose ol {
  margin-bottom: var(--space-md);
  padding-left: var(--space-lg);
}

.prose li {
  margin-bottom: var(--space-xs);
  line-height: 1.7;
}

.prose blockquote {
  border-left: 3px solid var(--color-primary-light);
  margin: var(--space-lg) 0;
  padding: var(--space-md) var(--space-lg);
  color: var(--color-muted);
  font-style: italic;
  background: var(--color-surface-raised);
  border-radius: 0 var(--radius) var(--radius) 0;
}

.prose em {
  font-style: italic;
}

.prose strong {
  font-weight: 600;
  color: var(--color-heading);
}

.prose hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-xl) 0;
}

/* Callout Boxes */
.callout {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-lg) 0;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

.callout__icon {
  font-size: 1.25rem;
  flex-shrink: 0;
}

.callout__content p:last-child {
  margin-bottom: 0;
}

/* Related Articles */
.related-articles {
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border);
  max-width: var(--content-width);
  margin-left: auto;
  margin-right: auto;
}

.related-articles__heading {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  color: var(--color-heading);
  margin-bottom: var(--space-md);
}

.related-articles__grid {
  display: grid;
  gap: var(--space-md);
  grid-template-columns: 1fr;
}

.related-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  padding: var(--space-md);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  text-decoration: none;
  transition: border-color var(--transition);
}

.related-card:hover {
  border-color: var(--color-accent);
}

.related-card__series {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--color-series);
}

.related-card__title {
  font-family: var(--font-heading);
  font-size: 1rem;
  color: var(--color-heading);
}

/* ── Footer ── */
.site-footer {
  margin-top: var(--space-2xl);
  padding: var(--space-xl) 0;
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}

.footer-grid {
  display: grid;
  gap: var(--space-lg);
  grid-template-columns: 1fr;
}

.footer-brand__tagline {
  color: var(--color-muted);
  margin-top: var(--space-sm);
  font-size: 0.9rem;
}

.footer-heading {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: var(--space-sm);
}

.footer-links ul {
  list-style: none;
}

.footer-links a {
  color: var(--color-muted);
  text-decoration: none;
  font-size: 0.9rem;
  line-height: 1.8;
}

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

.footer-bottom {
  margin-top: var(--space-xl);
  padding-top: var(--space-md);
  border-top: 1px solid var(--color-border);
  font-size: 0.8rem;
  color: var(--color-muted);
}

/* ── Responsive: Tablet (640px+) ── */
@media (min-width: 640px) {
  .card-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .related-articles__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer-grid {
    grid-template-columns: 2fr 1fr 1fr;
  }
}

/* ── Responsive: Desktop (1024px+) ── */
@media (min-width: 1024px) {
  .nav-toggle {
    display: none;
  }

  .nav-menu {
    display: flex;
    flex-direction: row;
    position: static;
    background: none;
    border: none;
    padding: 0;
    gap: 0;
  }

  .nav-item--has-children {
    position: relative;
  }

  .nav-dropdown {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background: var(--color-surface-raised);
    border: 1px solid var(--color-border);
    border-top: 3px solid var(--color-secondary);
    border-radius: 0 0 var(--radius) var(--radius);
    padding: var(--space-sm);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
    z-index: 50;
  }

  .nav-item--has-children:hover .nav-dropdown,
  .nav-item--has-children:focus-within .nav-dropdown {
    display: block;
  }

  .nav-item--has-children:hover .nav-chevron {
    transform: rotate(180deg);
  }

  .card-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  /* TOC shows on desktop */
  .toc {
    display: block;
  }
}

/* ── Responsive: Mobile-only TOC behavior ── */
@media (max-width: 1023px) {
  .article-layout {
    flex-direction: column;
  }

  .toc {
    width: 100%;
    position: static;
    margin-bottom: var(--space-lg);
  }

  .toc__wrapper[open] .toc__heading {
    margin-bottom: var(--space-sm);
  }

  /* Collapse TOC on mobile by default */
  .toc__wrapper:not([open]) .toc__nav {
    display: none;
  }

  .site-logo__text {
    font-size: 0.95rem;
  }
}

/* ── Print Styles ── */
@media print {
  .site-header,
  .site-footer,
  .toc,
  .reading-progress,
  .theme-toggle,
  .related-articles {
    display: none;
  }

  body {
    font-size: 12pt;
    color: #000;
    background: #fff;
  }

  .article-layout {
    display: block;
  }
}

/* ── Reduced Motion ── */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}