/* =========================================================
   CSS Custom Properties
   ========================================================= */
:root {
  --color-primary:     #6366f1;
  --color-primary-dark:#4f46e5;
  --color-secondary:   #06b6d4;
  --color-accent:      #8b5cf6;
  --color-accent2:     #3b82f6;
  --color-success:     #10b981;
  --color-warning:     #f59e0b;

  --color-bg:          #f8fafc;
  --color-surface:     #ffffff;
  --color-surface-2:   #f1f5f9;
  --color-border:      #e2e8f0;
  --color-border-light:#f1f5f9;

  --color-text:        #0f172a;
  --color-text-2:      #334155;
  --color-text-muted:  #64748b;
  --color-text-light:  #94a3b8;

  --header-height:     64px;
  --radius-sm:         6px;
  --radius-md:         10px;
  --radius-lg:         16px;
  --shadow-sm:         0 1px 3px rgba(0,0,0,.07), 0 1px 2px rgba(0,0,0,.04);
  --shadow-md:         0 4px 16px rgba(0,0,0,.08);
  --shadow-lg:         0 10px 40px rgba(0,0,0,.10);

  --font-sans:         'Inter', system-ui, -apple-system, sans-serif;
  --font-mono:         'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;

  --max-width:         1400px;
  --content-max:       900px;
  --gutter:            clamp(16px, 4vw, 48px);

  --transition:        150ms ease;
}

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

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

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  padding-top: var(--header-height);
}

img, svg { display: block; max-width: 100%; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { color: var(--color-primary-dark); }
ul, ol { padding-left: 1.5rem; }
li { margin-bottom: .25rem; }

/* =========================================================
   Typography — Google Font import
   ========================================================= */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

/* =========================================================
   STICKY HEADER
   ========================================================= */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-height);
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  box-shadow: var(--shadow-sm);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--gutter);
  height: 100%;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.logo-link {
  display: flex;
  align-items: center;
  gap: .6rem;
  color: var(--color-text);
  font-weight: 700;
  font-size: 1rem;
  text-decoration: none;
  flex-shrink: 0;
  transition: opacity var(--transition);
}
.logo-link:hover { opacity: .8; color: var(--color-text); }
.site-name { display: none; }
@media (min-width: 640px) { .site-name { display: inline; } }

.main-nav { margin-left: auto; }
.nav-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  align-items: center;
  gap: .25rem;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: .4rem;
  padding: .5rem .85rem;
  border-radius: var(--radius-sm);
  color: var(--color-text-2);
  font-size: .9rem;
  font-weight: 500;
  text-decoration: none;
  transition: background var(--transition), color var(--transition);
}
.nav-link:hover {
  background: var(--color-surface-2);
  color: var(--color-primary);
}
.nav-link--active {
  background: linear-gradient(135deg, #ede9fe, #e0f2fe);
  color: var(--color-primary);
}
.nav-icon { width: 16px; height: 16px; flex-shrink: 0; }

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  margin-left: auto;
  background: none;
  border: none;
  cursor: pointer;
  padding: .5rem;
  border-radius: var(--radius-sm);
}
.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}
.hamburger { position: relative; }
.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  left: 0;
}
.hamburger::before { top: -6px; }
.hamburger::after  { top: 6px; }

@media (max-width: 768px) {
  .nav-toggle { display: flex; align-items: center; }
  .main-nav {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0; right: 0;
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
    padding: .75rem var(--gutter);
  }
  .main-nav.nav-open { display: block; }
  .nav-list { flex-direction: column; align-items: stretch; gap: .25rem; }
  .nav-link { justify-content: flex-start; padding: .7rem 1rem; }
}

/* =========================================================
   MAIN CONTENT
   ========================================================= */
#main-content {
  flex: 1;
  width: 100%;
}

/* =========================================================
   HERO SECTION
   ========================================================= */
.hero {
  background: linear-gradient(135deg, #eef2ff 0%, #e0f2fe 50%, #f0fdf4 100%);
  padding: clamp(48px, 8vw, 96px) var(--gutter);
  text-align: center;
}
.hero-inner {
  max-width: 800px;
  margin: 0 auto;
}
.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--color-primary);
  background: rgba(99,102,241,.1);
  padding: .3rem .8rem;
  border-radius: 999px;
  margin-bottom: 1.25rem;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 800;
  line-height: 1.15;
  color: var(--color-text);
  margin-bottom: 1.25rem;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-description {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--color-text-2);
  max-width: 640px;
  margin: 0 auto 2rem;
  line-height: 1.7;
}
.hero-cta {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .75rem 1.5rem;
  border-radius: var(--radius-md);
  font-size: .95rem;
  font-weight: 600;
  text-decoration: none;
  transition: transform var(--transition), box-shadow var(--transition), opacity var(--transition);
  cursor: pointer;
  border: none;
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: #fff;
}
.btn-secondary {
  background: linear-gradient(135deg, var(--color-secondary), var(--color-accent2));
  color: #fff;
}
.btn-outline {
  background: var(--color-surface);
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}
.btn-icon { width: 20px; height: 20px; }

/* =========================================================
   HOME — SECTION CARDS
   ========================================================= */
.sections-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: clamp(32px, 5vw, 64px) var(--gutter);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 480px), 1fr));
  gap: 1.5rem;
}
.section-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 2rem;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  text-decoration: none;
  color: inherit;
  display: block;
}
.section-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
  color: inherit;
}
.section-card-icon {
  width: 48px; height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}
.section-card-icon svg { width: 24px; height: 24px; }
.icon-fundamentals { background: linear-gradient(135deg, #ede9fe, #c7d2fe); color: var(--color-primary); }
.icon-buildtools   { background: linear-gradient(135deg, #e0f2fe, #bae6fd); color: var(--color-secondary); }
.section-card h2 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: .5rem;
  color: var(--color-text);
}
.section-card p {
  font-size: .9rem;
  color: var(--color-text-muted);
  line-height: 1.6;
  margin: 0;
}
.section-card-topics {
  margin-top: 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: .4rem;
}
.topic-tag {
  font-size: .75rem;
  background: var(--color-surface-2);
  color: var(--color-text-muted);
  padding: .2rem .6rem;
  border-radius: 999px;
}

/* =========================================================
   HOME — INTRO + TOPICS GRID
   ========================================================= */
.home-intro {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--gutter) clamp(24px, 4vw, 48px);
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}
.home-intro p {
  font-size: 1rem;
  color: var(--color-text-2);
  line-height: 1.75;
}

.topics-section {
  background: var(--color-surface-2);
  padding: clamp(32px, 5vw, 64px) var(--gutter);
}
.topics-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}
.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: .5rem;
}
.section-title::after {
  content: '';
  flex: 1;
  height: 2px;
  background: var(--color-border);
  border-radius: 2px;
  margin-left: .5rem;
}
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 280px), 1fr));
  gap: 1rem;
}
.topic-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
  text-decoration: none;
  color: inherit;
  display: flex;
  align-items: flex-start;
  gap: .75rem;
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}
.topic-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
  color: inherit;
}
.topic-card-icon {
  width: 36px; height: 36px;
  flex-shrink: 0;
  border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem;
}
.topic-card h3 { font-size: .9rem; font-weight: 600; color: var(--color-text); line-height: 1.4; }
.topic-card p  { font-size: .8rem; color: var(--color-text-muted); margin-top: .25rem; line-height: 1.5; }

/* =========================================================
   CONTENT LAYOUT
   ========================================================= */
.content-wrapper {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: clamp(20px, 4vw, 48px) var(--gutter);
}

/* =========================================================
   BREADCRUMBS
   ========================================================= */
.breadcrumbs { margin-bottom: 1.5rem; }
.breadcrumb-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .25rem;
  font-size: .8rem;
}
.breadcrumb-item a {
  display: flex;
  align-items: center;
  gap: .25rem;
  color: var(--color-text-muted);
  text-decoration: none;
  padding: .2rem .4rem;
  border-radius: var(--radius-sm);
  transition: background var(--transition), color var(--transition);
}
.breadcrumb-item a:hover {
  background: var(--color-surface-2);
  color: var(--color-primary);
}
.breadcrumb-sep { color: var(--color-text-light); font-size: .85rem; }
.breadcrumb-item--current span { color: var(--color-text-2); font-weight: 500; padding: .2rem .4rem; }

/* =========================================================
   CONTENT BODY — Article
   ========================================================= */
.content-body {
  width: 100%;
}

/* H1 — colorful gradient */
.content-body h1 {
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  padding-bottom: .25rem;
}

/* Anchored headings scroll offset — accounts for sticky header height only */
.content-body h1,
.content-body h2,
.content-body h3,
.content-body h4,
.content-body h5,
.content-body h6 {
  scroll-margin-top: calc(var(--header-height) + 12px);
}

.content-body h2 {
  font-size: clamp(1.3rem, 3vw, 1.75rem);
  font-weight: 700;
  color: var(--color-text);
  margin: 2.5rem 0 1rem;
  padding-bottom: .5rem;
  border-bottom: 2px solid var(--color-border);
  position: relative;
}
.content-body h2::before {
  content: '';
  position: absolute;
  bottom: -2px; left: 0;
  width: 56px; height: 2px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: 2px;
}

.content-body h3 {
  font-size: clamp(1.05rem, 2.5vw, 1.3rem);
  font-weight: 600;
  color: var(--color-text);
  margin: 2rem 0 .75rem;
}
.content-body h4 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text-2);
  margin: 1.5rem 0 .5rem;
}

.content-body p {
  color: var(--color-text-2);
  margin-bottom: 1.25rem;
  font-size: 1rem;
  line-height: 1.8;
}

.content-body a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
  transition: color var(--transition), text-decoration-color var(--transition);
}
.content-body a:hover {
  color: var(--color-primary-dark);
  text-decoration-thickness: 2px;
}

.content-body ul,
.content-body ol {
  margin-bottom: 1.25rem;
  color: var(--color-text-2);
}
.content-body li { margin-bottom: .4rem; line-height: 1.7; }

/* strong inline */
.content-body strong { color: var(--color-text); font-weight: 600; }
.content-body em { font-style: italic; color: var(--color-text-2); }

/* =========================================================
   TABLES
   ========================================================= */
.table-wrapper {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin-bottom: 1.5rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}
.content-body table {
  width: 100%;
  border-collapse: collapse;
  font-size: .875rem;
  min-width: 540px;
}
.content-body thead {
  background: linear-gradient(135deg, #eef2ff, #e0f2fe);
}
.content-body th {
  padding: .75rem 1rem;
  text-align: left;
  font-weight: 600;
  color: var(--color-text);
  font-size: .8rem;
  letter-spacing: .04em;
  text-transform: uppercase;
  white-space: nowrap;
  border-bottom: 2px solid var(--color-border);
}
.content-body td {
  padding: .65rem 1rem;
  color: var(--color-text-2);
  border-bottom: 1px solid var(--color-border-light);
  vertical-align: top;
  line-height: 1.6;
}
.content-body tr:last-child td { border-bottom: none; }
.content-body tbody tr:hover { background: var(--color-surface-2); }
.content-body code {
  font-family: var(--font-mono);
  font-size: .825rem;
  background: var(--color-surface-2);
  color: var(--color-primary);
  padding: .15em .4em;
  border-radius: 4px;
  border: 1px solid var(--color-border);
}

/* =========================================================
   CODE BLOCKS
   ========================================================= */
.content-body pre {
  position: relative;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  margin: 1.5rem 0;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  background: #f8f9fc !important;
}
.content-body pre code {
  font-family: var(--font-mono);
  font-size: .83rem;
  line-height: 1.7;
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  display: block;
  overflow-x: auto;
  padding: 1.25rem 1.5rem;
  -webkit-overflow-scrolling: touch;
}

/* Code copy button */
.copy-btn {
  position: absolute;
  top: .6rem;
  right: .6rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: .3rem .6rem;
  font-size: .72rem;
  font-weight: 500;
  color: var(--color-text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: .3rem;
  transition: background var(--transition), color var(--transition), border-color var(--transition), opacity var(--transition);
  opacity: 0;
}
.content-body pre:hover .copy-btn,
.copy-btn:focus { opacity: 1; }
.copy-btn:hover {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}
.copy-btn svg { width: 13px; height: 13px; }
.copy-btn.copied {
  background: var(--color-success);
  color: #fff;
  border-color: var(--color-success);
  opacity: 1;
}

/* Language label */
.code-lang {
  position: absolute;
  top: .6rem;
  left: 1rem;
  font-size: .7rem;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--color-text-light);
}

/* =========================================================
   FAQ ACCORDIONS
   ========================================================= */
.accordion-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  margin-bottom: .75rem;
  overflow: hidden;
  transition: box-shadow var(--transition);
}
.accordion-item:hover { box-shadow: var(--shadow-sm); }

.accordion-trigger {
  width: 100%;
  background: var(--color-surface-2);
  border: none;
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  cursor: pointer;
  text-align: left;
  font-size: .95rem;
  font-weight: 600;
  color: var(--color-text);
  transition: background var(--transition);
}
.accordion-trigger:hover { background: #ede9fe; }
.accordion-trigger[aria-expanded="true"] { background: #ede9fe; color: var(--color-primary); }

.accordion-icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  transition: transform .25s ease;
  color: var(--color-text-muted);
}
.accordion-trigger[aria-expanded="true"] .accordion-icon {
  transform: rotate(180deg);
  color: var(--color-primary);
}

.accordion-panel {
  max-height: 0;
  overflow: hidden;
  transition: max-height .3s ease;
}
.accordion-panel-inner {
  padding: 1rem 1.25rem 1.25rem;
  font-size: .9rem;
  color: var(--color-text-2);
  line-height: 1.75;
  background: var(--color-surface);
}
.accordion-panel-inner p { margin-bottom: .75rem; }
.accordion-panel-inner p:last-child { margin-bottom: 0; }

/* =========================================================
   INTERACTIVE CHECKBOXES
   ========================================================= */
input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 17px;
  height: 17px;
  border: 2px solid var(--color-border);
  border-radius: 4px;
  cursor: pointer;
  vertical-align: middle;
  position: relative;
  flex-shrink: 0;
  margin-right: .4rem;
  transition: background var(--transition), border-color var(--transition);
  background: var(--color-surface);
}
input[type="checkbox"]:hover { border-color: var(--color-primary); }
input[type="checkbox"]:checked {
  background: var(--color-primary);
  border-color: var(--color-primary);
}
input[type="checkbox"]:checked::after {
  content: '';
  position: absolute;
  top: 2px; left: 4px;
  width: 5px; height: 9px;
  border: 2px solid #fff;
  border-top: none; border-left: none;
  transform: rotate(45deg);
}

.task-list { list-style: none; padding: 0; }
.task-list-item {
  display: flex;
  align-items: flex-start;
  gap: .4rem;
  margin-bottom: .5rem;
  padding: .3rem 0;
}
.task-list-item label { cursor: pointer; color: var(--color-text-2); line-height: 1.5; }
.task-list-item:has(input:checked) label {
  text-decoration: line-through;
  color: var(--color-text-light);
}

/* =========================================================
   FOOTER
   ========================================================= */
.site-footer {
  background: var(--color-text);
  color: var(--color-text-light);
  margin-top: auto;
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: clamp(32px, 5vw, 56px) var(--gutter) clamp(24px, 4vw, 40px);
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.5rem;
}
@media (min-width: 768px) {
  .footer-inner { grid-template-columns: 1.5fr 2fr; }
}
.footer-brand {
  display: flex;
  flex-direction: column;
  gap: .75rem;
}
.footer-brand .site-logo path, .footer-brand .site-logo text { /* keep logo colors */ }
.footer-site-name {
  font-size: 1rem;
  font-weight: 700;
  color: #fff;
}
.footer-tagline {
  font-size: .85rem;
  line-height: 1.7;
  color: #94a3b8;
}
.footer-nav {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 2rem;
}
.footer-heading {
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: #e2e8f0;
  margin-bottom: .85rem;
}
.footer-nav ul { list-style: none; padding: 0; }
.footer-nav li { margin-bottom: .45rem; }
.footer-nav a {
  font-size: .85rem;
  color: #94a3b8;
  text-decoration: none;
  transition: color var(--transition);
}
.footer-nav a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid #1e293b;
  padding: 1rem var(--gutter);
  text-align: center;
  font-size: .78rem;
  color: #475569;
}
.footer-bottom p { margin: 0; }

/* =========================================================
   PRISM OVERRIDES — match site palette
   ========================================================= */
pre[class*="language-"],
code[class*="language-"] {
  background: #f8f9fc !important;
  color: #334155 !important;
}
.token.comment,
.token.prolog,
.token.doctype,
.token.cdata { color: #94a3b8; }
.token.keyword,
.token.rule { color: var(--color-primary); font-weight: 600; }
.token.string,
.token.attr-value { color: #059669; }
.token.number,
.token.boolean { color: #d97706; }
.token.function { color: #7c3aed; }
.token.class-name { color: var(--color-secondary); }
.token.operator,
.token.punctuation { color: #64748b; }
.token.property { color: #0369a1; }
.token.selector { color: var(--color-accent); }
.token.tag { color: var(--color-accent2); }
.token.attr-name { color: var(--color-primary); }

/* =========================================================
   UTILITY
   ========================================================= */
.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;
}