/* ============================================================
   Design Tokens
   ============================================================ */
:root {
  --color-purple:    #6B2FD9;
  --color-purple-lt: #EDE8FA;
  --color-red:       #E8334A;
  --color-red-lt:    #FDEAEC;
  --color-yellow:    #F5C518;
  --color-yellow-lt: #FEF8DC;
  --color-turquoise: #00C2B2;
  --color-turquoise-lt: #E0F8F6;
  --color-green:     #2ECC5A;
  --color-green-lt:  #E4F9EB;

  --color-bg:        #F7F8FC;
  --color-surface:   #FFFFFF;
  --color-text:      #0F1120;
  --color-muted:     #6B7280;
  --color-border:    #E2E5EF;
  --color-code-bg:   #F3F4F8;

  --font-sans: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "Cascadia Code", Consolas, monospace;

  --header-height:   64px;
  --content-max:     1400px;
  --radius:          10px;
  --shadow-sm:       0 1px 4px rgba(0,0,0,.06);
  --shadow-md:       0 4px 20px rgba(0,0,0,.10);
  --shadow-lg:       0 8px 40px rgba(0,0,0,.13);
  --transition:      0.2s 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;
}

img, svg { display: block; max-width: 100%; }
a { color: var(--color-purple); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ============================================================
   Layout Container
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 clamp(1rem, 4vw, 3rem);
}

main { flex: 1; }

/* ============================================================
   Typography
   ============================================================ */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.25;
  color: var(--color-text);
  scroll-margin-top: calc(var(--header-height) + 1.5rem);
}

h1 { font-size: clamp(1.9rem, 4vw, 2.8rem); margin: 0 0 1.25rem; }
h2 { font-size: clamp(1.4rem, 3vw, 2rem);   margin: 2.5rem 0 1rem; color: var(--color-purple); }
h3 { font-size: clamp(1.1rem, 2vw, 1.4rem); margin: 2rem 0 0.75rem; color: var(--color-text); }
h4 { font-size: 1.1rem; margin: 1.5rem 0 0.5rem; }

p { margin: 0 0 1.2rem; }
p:last-child { margin-bottom: 0; }

strong { font-weight: 700; }
em     { font-style: italic; }

blockquote {
  border-left: 4px solid var(--color-purple);
  padding: 0.75rem 1.25rem;
  background: var(--color-purple-lt);
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 1.5rem 0;
  color: var(--color-muted);
  font-style: italic;
}

hr {
  border: none;
  border-top: 2px solid var(--color-border);
  margin: 2.5rem 0;
}

ul, ol {
  padding-left: 1.5rem;
  margin: 0 0 1.2rem;
}
li { margin-bottom: 0.35rem; }
li > ul, li > ol { margin-bottom: 0; }

/* ============================================================
   Links
   ============================================================ */
.article-body a,
.prose a {
  color: var(--color-purple);
  text-decoration: underline;
  text-decoration-thickness: 1.5px;
  text-underline-offset: 3px;
  transition: color var(--transition), text-decoration-color var(--transition);
}
.article-body a:hover,
.prose a:hover {
  color: var(--color-red);
  text-decoration-color: var(--color-red);
}

/* ============================================================
   Sticky Header
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 200;
  height: var(--header-height);
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1.5px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.site-header .container {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  height: 100%;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  flex-shrink: 0;
}
.site-logo svg { width: 38px; height: 38px; }
.site-logo-text {
  font-size: 1rem;
  font-weight: 800;
  line-height: 1.2;
  color: var(--color-text);
  letter-spacing: -0.01em;
}
.site-logo-text span { color: var(--color-purple); }
.site-logo:hover .site-logo-text { color: var(--color-purple); }

/* nav element wrapping the ul */
.site-header nav {
  display: flex;
  align-items: center;
  height: 100%;
  margin-left: auto;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  list-style: none;
  padding: 0;
  margin: 0;
  height: 100%;
}

.site-nav li {
  display: flex;
  align-items: center;
  height: 100%;
}

.site-nav a {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.75rem;
  border-radius: 6px;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-muted);
  text-decoration: none;
  transition: background var(--transition), color var(--transition);
  white-space: nowrap;
}
.site-nav a:hover {
  background: var(--color-purple-lt);
  color: var(--color-purple);
  text-decoration: none;
}
.site-nav a.active {
  background: var(--color-purple-lt);
  color: var(--color-purple);
}
.site-nav .nav-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  display: inline-block;
  flex-shrink: 0;
}
.nav-purple .nav-dot { background: var(--color-purple); }
.nav-red    .nav-dot { background: var(--color-red); }
.nav-green  .nav-dot { background: var(--color-green); }

/* Hamburger */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  margin-left: auto;
  flex-direction: column;
  gap: 5px;
}
.nav-toggle span {
  display: block;
  width: 24px; height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

/* ============================================================
   Breadcrumbs
   ============================================================ */
.breadcrumbs {
  font-size: 0.82rem;
  color: var(--color-muted);
  padding: 0.85rem 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.3rem;
}
.breadcrumbs a {
  color: var(--color-muted);
  text-decoration: none;
  transition: color var(--transition);
}
.breadcrumbs a:hover { color: var(--color-purple); }
.breadcrumbs .sep { color: var(--color-border); }
.breadcrumbs .current { color: var(--color-text); font-weight: 600; }

/* ============================================================
   Article / Page Layout
   ============================================================ */
.page-wrapper {
  padding: 2rem 0 4rem;
}

.article-header {
  margin-bottom: 2.5rem;
}
.article-header h1 {
  background: linear-gradient(135deg, var(--color-purple), var(--color-red));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.article-body { max-width: 100%; }

/* First h1 inside an article gets the gradient treatment */
.article-body > h1:first-child,
.article-body h1 {
  background: linear-gradient(135deg, var(--color-purple), var(--color-red));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1.75rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid var(--color-border);
}

/* Section index card grid */
.section-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.25rem;
  margin: 2rem 0;
}

.topic-card {
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-decoration: none;
  color: var(--color-text);
  transition: box-shadow var(--transition), border-color var(--transition), transform var(--transition);
  display: block;
}
.topic-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-purple);
  transform: translateY(-2px);
  text-decoration: none;
}
.topic-card h3 {
  margin: 0.5rem 0 0.35rem;
  color: var(--color-purple);
  font-size: 1rem;
}
.topic-card p { font-size: 0.88rem; color: var(--color-muted); margin: 0; }

/* ============================================================
   Code Blocks
   ============================================================ */
pre {
  position: relative;
  background: var(--color-code-bg) !important;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem 1.25rem 1.25rem 1.25rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-family: var(--font-mono);
  font-size: 0.87rem;
  line-height: 1.65;
}
code {
  font-family: var(--font-mono);
  font-size: 0.87em;
  background: var(--color-code-bg);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 0.15em 0.4em;
  color: var(--color-red);
}
pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  font-size: inherit;
  border-radius: 0;
}

/* Copy button */
.copy-btn {
  position: absolute;
  top: 0.6rem;
  right: 0.6rem;
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: 6px;
  padding: 0.3rem 0.65rem;
  font-size: 0.75rem;
  font-family: var(--font-sans);
  font-weight: 600;
  color: var(--color-muted);
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition);
  opacity: 0;
  pointer-events: none;
}
pre:hover .copy-btn,
pre:focus-within .copy-btn {
  opacity: 1;
  pointer-events: auto;
}
.copy-btn:hover {
  background: var(--color-purple-lt);
  color: var(--color-purple);
  border-color: var(--color-purple);
}
.copy-btn.copied {
  background: var(--color-green-lt);
  color: var(--color-green);
  border-color: var(--color-green);
  opacity: 1;
  pointer-events: none;
}

/* language label shown as ::before on pre */
pre[class*="language-"]::before {
  content: attr(data-lang);
  position: absolute;
  top: 0.6rem;
  left: 1rem;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-muted);
  opacity: 0.6;
}

/* ============================================================
   Tables
   ============================================================ */
.table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: var(--radius);
  border: 1.5px solid var(--color-border);
  margin: 1.5rem 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
thead tr {
  background: linear-gradient(90deg, var(--color-purple-lt), var(--color-turquoise-lt));
}
thead th {
  padding: 0.75rem 1rem;
  text-align: left;
  font-weight: 700;
  color: var(--color-purple);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  white-space: nowrap;
}
tbody tr { border-top: 1px solid var(--color-border); }
tbody tr:hover { background: var(--color-purple-lt); }
tbody td { padding: 0.65rem 1rem; vertical-align: top; }

/* auto-wrap tables in article body — overflow handled by .table-wrap, not display:block */
.article-body table {
  width: 100%;
  min-width: 100%;
}
.article-body .table-wrap {
  width: 100%;
  display: block;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

/* ============================================================
   FAQ / Accordions (details/summary)
   ============================================================ */
details {
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius);
  margin: 0.75rem 0;
  background: var(--color-surface);
  overflow: hidden;
  transition: box-shadow var(--transition);
}
details[open] {
  box-shadow: var(--shadow-sm);
  border-color: var(--color-purple);
}
summary {
  list-style: none;
  cursor: pointer;
  padding: 1rem 1.25rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  color: var(--color-text);
  transition: background var(--transition), color var(--transition);
  user-select: none;
}
summary::-webkit-details-marker { display: none; }
summary::after {
  content: "＋";
  font-size: 1.1rem;
  font-weight: 400;
  color: var(--color-purple);
  flex-shrink: 0;
  transition: transform var(--transition);
}
details[open] summary::after {
  content: "－";
}
summary:hover { background: var(--color-purple-lt); color: var(--color-purple); }
details > *:not(summary) {
  padding: 0 1.25rem 1.25rem;
}

/* ============================================================
   Interactive Checkboxes
   ============================================================ */
.article-body input[type="checkbox"],
input[type="checkbox"].task-checkbox {
  appearance: none;
  -webkit-appearance: none;
  width: 1.1rem;
  height: 1.1rem;
  border: 2px solid var(--color-purple);
  border-radius: 3px;
  cursor: pointer;
  vertical-align: middle;
  position: relative;
  margin-right: 0.45rem;
  flex-shrink: 0;
  transition: background var(--transition), border-color var(--transition);
}
.article-body input[type="checkbox"]:checked,
input[type="checkbox"].task-checkbox:checked {
  background: var(--color-purple);
  border-color: var(--color-purple);
}
.article-body input[type="checkbox"]:checked::after,
input[type="checkbox"].task-checkbox:checked::after {
  content: "✓";
  position: absolute;
  top: -1px; left: 1px;
  font-size: 0.75rem;
  color: #fff;
  font-weight: 700;
}
.article-body input[type="checkbox"]:hover {
  border-color: var(--color-red);
}

/* ============================================================
   Site Footer
   ============================================================ */
.site-footer {
  background: var(--color-text);
  color: rgba(255,255,255,0.7);
  padding: 3rem 0 1.5rem;
  margin-top: auto;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1fr repeat(3, auto);
  gap: 2.5rem;
  margin-bottom: 2rem;
  align-items: start;
}
.footer-brand .site-logo-text { color: #fff; }
.footer-brand .site-logo-text span { color: var(--color-yellow); }
.footer-brand p { margin-top: 0.65rem; font-size: 0.85rem; color: rgba(255,255,255,0.5); }

.footer-col h4 {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: rgba(255,255,255,0.4);
  margin-bottom: 0.75rem;
}
.footer-col ul { list-style: none; padding: 0; }
.footer-col li { margin-bottom: 0.4rem; }
.footer-col a {
  color: rgba(255,255,255,0.65);
  text-decoration: none;
  font-size: 0.87rem;
  transition: color var(--transition);
}
.footer-col a:hover { color: var(--color-yellow); }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8rem;
  color: rgba(255,255,255,0.35);
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* ============================================================
   Homepage — Hero
   ============================================================ */
.hero {
  padding: clamp(3rem, 8vw, 6rem) 0;
  text-align: center;
  background: linear-gradient(160deg, var(--color-bg) 0%, #EDE8FA 60%, #E0F8F6 100%);
}
.hero h1 {
  font-size: clamp(2rem, 5.5vw, 3.8rem);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--color-purple), var(--color-turquoise));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero .hero-sub {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--color-muted);
  max-width: 700px;
  margin: 0 auto 2.5rem;
  line-height: 1.75;
}
.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.8rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 700;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform var(--transition), box-shadow var(--transition);
  cursor: pointer;
  border: none;
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); text-decoration: none; }
.btn-purple { background: var(--color-purple); color: #fff; }
.btn-red    { background: var(--color-red);    color: #fff; }
.btn-green  { background: var(--color-green);  color: #fff; }
.btn-outline {
  background: transparent;
  color: var(--color-purple);
  border: 2px solid var(--color-purple);
}
.btn-outline:hover { background: var(--color-purple); color: #fff; }

/* ============================================================
   Homepage — Topic Cards
   ============================================================ */
.topics-section { padding: 4rem 0; }
.topics-section h2 {
  text-align: center;
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  margin-bottom: 2rem;
  color: var(--color-text);
}
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}
.topic-hero-card {
  background: var(--color-surface);
  border-radius: calc(var(--radius) * 1.5);
  padding: 2rem;
  box-shadow: var(--shadow-sm);
  border: 2px solid transparent;
  text-decoration: none;
  color: var(--color-text);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.topic-hero-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); text-decoration: none; }
.topic-hero-card.purple:hover { border-color: var(--color-purple); }
.topic-hero-card.red:hover    { border-color: var(--color-red); }
.topic-hero-card.green:hover  { border-color: var(--color-green); }

.topic-icon {
  width: 52px; height: 52px;
  border-radius: 12px;
  display: flex;
  align-items: center; justify-content: center;
  font-size: 1.5rem;
}
.topic-icon.purple { background: var(--color-purple-lt); }
.topic-icon.red    { background: var(--color-red-lt); }
.topic-icon.green  { background: var(--color-green-lt); }

.topic-hero-card h3 {
  margin: 0;
  font-size: 1.15rem;
  color: var(--color-text);
}
.topic-hero-card p {
  font-size: 0.9rem;
  color: var(--color-muted);
  margin: 0;
  flex: 1;
}
.card-arrow {
  font-size: 0.85rem;
  font-weight: 700;
  margin-top: auto;
}
.purple .card-arrow { color: var(--color-purple); }
.red    .card-arrow { color: var(--color-red); }
.green  .card-arrow { color: var(--color-green); }

/* ============================================================
   Homepage — Featured Articles
   ============================================================ */
.featured-section { padding: 3rem 0 4rem; background: var(--color-surface); }
.featured-section h2 { text-align: center; margin-bottom: 2rem; color: var(--color-text); }
.featured-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1rem;
}
.featured-tile {
  background: var(--color-bg);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  text-decoration: none;
  color: var(--color-text);
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  transition: box-shadow var(--transition), border-color var(--transition), transform var(--transition);
}
.featured-tile:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
  text-decoration: none;
}
.featured-tile.purple:hover { border-color: var(--color-purple); }
.featured-tile.red:hover    { border-color: var(--color-red); }
.featured-tile.green:hover  { border-color: var(--color-green); }
.featured-tag {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.featured-tag.purple { color: var(--color-purple); }
.featured-tag.red    { color: var(--color-red); }
.featured-tag.green  { color: var(--color-green); }
.featured-tile strong { font-size: 0.93rem; line-height: 1.4; }
.featured-tile span { font-size: 0.82rem; color: var(--color-muted); }

/* ============================================================
   Homepage — Intro paragraphs
   ============================================================ */
.intro-section {
  padding: 3.5rem 0;
  background: var(--color-bg);
}
.intro-section .intro-inner {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}
.intro-section p {
  color: var(--color-muted);
  font-size: 1rem;
  line-height: 1.8;
}

/* ============================================================
   Section landing — sub-page list
   ============================================================ */
.subpage-list {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin: 1.5rem 0;
}
.subpage-list li a {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.75rem 1rem;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  color: var(--color-text);
  font-weight: 600;
  font-size: 0.93rem;
  text-decoration: none;
  transition: background var(--transition), border-color var(--transition), transform var(--transition);
}
.subpage-list li a:hover {
  background: var(--color-purple-lt);
  border-color: var(--color-purple);
  transform: translateX(4px);
  text-decoration: none;
}
.subpage-list li a::before {
  content: "→";
  color: var(--color-purple);
  font-weight: 700;
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 900px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 768px) {
  .site-nav {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0; right: 0;
    background: var(--color-surface);
    flex-direction: column;
    align-items: stretch;
    padding: 1rem;
    border-bottom: 1.5px solid var(--color-border);
    box-shadow: var(--shadow-md);
    gap: 0.25rem;
  }
  .site-nav.open { display: flex; }
  .site-nav a { padding: 0.65rem 1rem; font-size: 0.95rem; }
  .nav-toggle { display: flex; }
  .footer-grid { grid-template-columns: 1fr; }
  .hero-ctas { flex-direction: column; align-items: stretch; }
  .hero-ctas .btn { justify-content: center; }
}
@media (min-width: 1600px) {
  :root { --content-max: 1560px; }
}