/* =============================================================================
   SPC Automation & Quality Engineering Hub
   Light, professional palette — control-chart inspired
   ========================================================================== */

:root {
  --color-primary: #1e6091;
  --color-primary-700: #154868;
  --color-primary-100: #e8f1f8;
  --color-accent: #2a9d8f;
  --color-accent-100: #e6f5f1;
  --color-warning: #e76f51;
  --color-warning-100: #fdeee7;
  --color-gold: #ffd166;

  --color-bg: #fbfcfd;
  --color-surface: #ffffff;
  --color-surface-2: #f6f9fc;
  --color-border: #e3eaf1;
  --color-text: #13293d;
  --color-text-muted: #5a6b7c;
  --color-link: #1e6091;
  --color-link-hover: #154868;

  --color-code-bg: #f1f5f9;
  --color-code-block-bg: #f6faff;
  --color-code-border: #dde7f1;
  --color-inline-code-bg: #eef3f8;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  --font-mono: "SFMono-Regular", Menlo, Consolas, "Liberation Mono", Monaco, monospace;

  --header-h: 68px;
  --radius: 10px;
  --radius-lg: 16px;
  --shadow-sm: 0 1px 2px rgba(19, 41, 61, 0.06), 0 2px 6px rgba(19, 41, 61, 0.04);
  --shadow-md: 0 4px 14px rgba(19, 41, 61, 0.08), 0 2px 4px rgba(19, 41, 61, 0.04);
  --shadow-lg: 0 12px 32px rgba(19, 41, 61, 0.10), 0 4px 8px rgba(19, 41, 61, 0.06);

  --max-w: 1400px;
  --reading-max: 80ch;

  --t: 180ms ease;
}

/* Reset & base
   ----------------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.65;
  font-size: 16.5px;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}
img, svg { max-width: 100%; height: auto; }
hr { border: 0; border-top: 1px solid var(--color-border); margin: 2rem 0; }

a {
  color: var(--color-link);
  text-decoration: underline;
  text-decoration-color: rgba(30, 96, 145, 0.35);
  text-underline-offset: 3px;
  transition: color var(--t), text-decoration-color var(--t);
}
a:hover, a:focus-visible {
  color: var(--color-link-hover);
  text-decoration-color: var(--color-link-hover);
}

button { font-family: inherit; }

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-primary);
  color: #fff;
  padding: 0.65rem 1rem;
  z-index: 1000;
  border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { left: 0; }

/* Layout
   ----------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 clamp(1rem, 3vw, 2.5rem);
}
.site-main { flex: 1; padding: clamp(1.25rem, 3vw, 2.5rem) 0; }

/* Header
   ----------------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--color-border);
  min-height: var(--header-h);
}
.header-inner {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  min-height: var(--header-h);
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  color: var(--color-text);
  text-decoration: none;
  flex-shrink: 0;
}
.brand:hover { color: var(--color-primary); }
.brand-mark svg { width: 36px; height: 36px; display: block; border-radius: 8px; box-shadow: var(--shadow-sm); }
.brand-mark.small svg { width: 28px; height: 28px; }
.brand-text { display: flex; flex-direction: column; line-height: 1.2; }
.brand-name { font-weight: 700; font-size: 1.05rem; letter-spacing: -0.01em; }
.brand-sub { color: var(--color-text-muted); font-size: 0.78rem; }

.site-nav { margin-left: auto; }
.site-nav ul {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  list-style: none;
  padding: 0;
  margin: 0;
}
.site-nav a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 0.8rem;
  border-radius: 8px;
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  transition: background var(--t), color var(--t), transform var(--t);
}
.site-nav a:hover {
  background: var(--color-primary-100);
  color: var(--color-primary);
  transform: translateY(-1px);
}
.site-nav a[aria-current="page"] {
  background: var(--color-primary-100);
  color: var(--color-primary);
}
.nav-ico { width: 18px; height: 18px; color: var(--color-primary); flex-shrink: 0; }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-around;
  width: 38px;
  height: 38px;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  cursor: pointer;
  padding: 9px 7px;
}
.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform var(--t), opacity var(--t);
}

@media (max-width: 860px) {
  .site-nav { display: none; position: absolute; top: var(--header-h); left: 0; right: 0; background: #fff; border-bottom: 1px solid var(--color-border); padding: 0.75rem 1rem; }
  .site-nav.open { display: block; }
  .site-nav ul { flex-direction: column; align-items: stretch; gap: 0.25rem; }
  .nav-toggle { display: flex; }
  .brand-sub { display: none; }
}

/* Hero
   ----------------------------------------------------------------------- */
.hero {
  background:
    radial-gradient(1200px 400px at 80% -10%, rgba(42, 157, 143, 0.12), transparent 60%),
    radial-gradient(1000px 360px at 10% 0%, rgba(30, 96, 145, 0.10), transparent 65%),
    linear-gradient(180deg, #fbfcfd 0%, #f3f8fc 100%);
  border-bottom: 1px solid var(--color-border);
  padding: clamp(2rem, 6vw, 5rem) 0 clamp(2rem, 5vw, 4rem);
}
.hero-inner { text-align: center; }
.hero-logo {
  display: block;
  margin: 0 auto 1.5rem;
  width: clamp(96px, 14vw, 160px);
}
.hero-logo svg { width: 100%; height: auto; filter: drop-shadow(0 10px 24px rgba(30, 96, 145, 0.2)); transition: transform 400ms ease; }
.hero-logo:hover svg { transform: translateY(-3px) rotate(-1deg); }
.hero-title {
  font-size: clamp(1.9rem, 4.5vw, 3rem);
  line-height: 1.15;
  margin: 0 0 0.75rem;
  letter-spacing: -0.02em;
  background: linear-gradient(120deg, #1e6091 0%, #2a9d8f 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero-tagline {
  max-width: 70ch;
  margin: 0 auto 2rem;
  font-size: clamp(1rem, 1.4vw, 1.15rem);
  color: var(--color-text-muted);
}
.hero-ctas {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  max-width: 1100px;
  margin: 0 auto;
  text-align: left;
}
.cta-card {
  display: grid;
  grid-template-columns: 56px 1fr auto;
  gap: 1rem;
  align-items: center;
  padding: 1.1rem 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  text-decoration: none;
  color: var(--color-text);
  transition: transform var(--t), box-shadow var(--t), border-color var(--t);
}
.cta-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
  color: var(--color-text);
}
.cta-icon svg { width: 56px; height: 56px; display: block; }
.cta-title { display: block; font-weight: 700; color: var(--color-primary); font-size: 1rem; margin-bottom: 0.2rem; }
.cta-summary { display: block; color: var(--color-text-muted); font-size: 0.9rem; line-height: 1.45; }
.cta-arrow { font-size: 1.4rem; color: var(--color-accent); transition: transform var(--t); }
.cta-card:hover .cta-arrow { transform: translateX(4px); }

/* Intro & sections
   ----------------------------------------------------------------------- */
.intro { padding: clamp(2rem, 5vw, 3.5rem) 0 1.5rem; }
.intro h2 { font-size: clamp(1.4rem, 2.5vw, 1.8rem); margin: 0 0 1rem; color: var(--color-primary); }
.intro p { color: var(--color-text); }

.section-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.25rem;
  padding-bottom: 3rem;
}
.section-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  transition: transform var(--t), box-shadow var(--t);
}
.section-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.section-card h2 { font-size: 1.1rem; margin: 0 0 0.6rem; }
.section-card h2 a { color: var(--color-primary); text-decoration: none; }
.section-card h2 a:hover { text-decoration: underline; }
.section-card p { color: var(--color-text-muted); margin: 0 0 1rem; font-size: 0.95rem; }
.section-list { list-style: none; padding: 0; margin: 0; }
.section-list li { margin: 0.35rem 0; }
.section-list a {
  display: block;
  padding: 0.4rem 0.6rem;
  border-radius: 6px;
  text-decoration: none;
  color: var(--color-text);
  font-size: 0.92rem;
  border-left: 3px solid transparent;
  transition: background var(--t), border-color var(--t), color var(--t);
}
.section-list a:hover {
  background: var(--color-primary-100);
  border-left-color: var(--color-accent);
  color: var(--color-primary);
}

/* Article layout
   ----------------------------------------------------------------------- */
.article { padding-top: 1rem; }
.article-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: clamp(1.5rem, 3vw, 3rem);
  align-items: start;
  margin-top: 1rem;
}
@media (max-width: 1024px) {
  .article-grid { grid-template-columns: 1fr; }
}
.article-aside {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  position: sticky;
  top: calc(var(--header-h) + 1rem);
  box-shadow: var(--shadow-sm);
}
.article-aside h2 { font-size: 1rem; margin: 0 0 0.75rem; color: var(--color-primary); }
.related-list { list-style: none; padding: 0; margin: 0; }
.related-list li { margin: 0.3rem 0; }
.related-list a {
  display: block;
  padding: 0.4rem 0.5rem;
  border-radius: 6px;
  text-decoration: none;
  color: var(--color-text);
  font-size: 0.9rem;
  border-left: 3px solid transparent;
  transition: background var(--t), border-color var(--t);
}
.related-list a:hover { background: var(--color-primary-100); border-left-color: var(--color-accent); color: var(--color-primary); }

/* Breadcrumbs
   ----------------------------------------------------------------------- */
.breadcrumbs ol {
  list-style: none;
  padding: 0;
  margin: 0 0 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}
.breadcrumbs li + li::before { content: "›"; padding: 0 0.4rem; color: var(--color-text-muted); }
.breadcrumbs a {
  text-decoration: none;
  color: var(--color-text-muted);
  text-transform: capitalize;
}
.breadcrumbs a:hover { color: var(--color-primary); }
.breadcrumbs [aria-current="page"] { color: var(--color-text); font-weight: 500; text-transform: capitalize; }

/* Prose
   ----------------------------------------------------------------------- */
.prose { max-width: none; }
.prose > * { scroll-margin-top: calc(var(--header-h) + 1rem); }

.prose h1 {
  font-size: clamp(1.9rem, 3.5vw, 2.6rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 1.25rem;
  background: linear-gradient(120deg, #1e6091 0%, #2a9d8f 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.prose h2 {
  font-size: clamp(1.4rem, 2.2vw, 1.75rem);
  margin: 2.5rem 0 1rem;
  color: var(--color-primary-700);
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--color-border);
  letter-spacing: -0.01em;
}
.prose h3 {
  font-size: clamp(1.15rem, 1.8vw, 1.35rem);
  margin: 2rem 0 0.75rem;
  color: var(--color-primary);
}
.prose h4 { font-size: 1.1rem; margin: 1.5rem 0 0.5rem; color: var(--color-accent); }
.prose h5, .prose h6 { font-size: 1rem; margin: 1.25rem 0 0.5rem; color: var(--color-text); }

.prose p { margin: 0 0 1.15rem; }
.prose ul, .prose ol { padding-left: 1.4rem; margin: 0 0 1.15rem; }
.prose li { margin: 0.35rem 0; }

.prose a { font-weight: 500; }

.prose blockquote {
  margin: 1.5rem 0;
  padding: 0.75rem 1.25rem;
  border-left: 4px solid var(--color-accent);
  background: var(--color-accent-100);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--color-text);
}
.prose blockquote p:last-child { margin-bottom: 0; }

/* Inline code
   ----------------------------------------------------------------------- */
.prose :not(pre) > code {
  font-family: var(--font-mono);
  font-size: 0.92em;
  background: var(--color-inline-code-bg);
  padding: 0.12em 0.4em;
  border-radius: 4px;
  color: var(--color-primary-700);
  border: none;
}

/* Code blocks (Prism)
   ----------------------------------------------------------------------- */
.prose pre,
pre[class*="language-"] {
  position: relative;
  background: var(--color-code-block-bg);
  color: var(--color-text);
  border: 1px solid var(--color-code-border);
  border-radius: var(--radius);
  padding: 1.1rem 1.2rem;
  margin: 1.5rem 0;
  overflow-x: auto;
  font-size: 0.9rem;
  line-height: 1.6;
  box-shadow: var(--shadow-sm);
}
pre[class*="language-"] code,
.prose pre code {
  background: none;
  padding: 0;
  border-radius: 0;
  color: inherit;
  font-family: var(--font-mono);
  font-size: inherit;
}

/* Prism light token colors */
.token.comment, .token.prolog, .token.doctype, .token.cdata { color: #6a8090; font-style: italic; }
.token.punctuation { color: #5a6b7c; }
.token.property, .token.tag, .token.constant, .token.symbol, .token.deleted { color: #c0392b; }
.token.boolean, .token.number { color: #2a9d8f; }
.token.selector, .token.attr-name, .token.string, .token.char, .token.builtin, .token.inserted { color: #1e6091; }
.token.operator, .token.entity, .token.url, .language-css .token.string, .style .token.string { color: #154868; }
.token.atrule, .token.attr-value, .token.keyword { color: #6f42c1; font-weight: 600; }
.token.function, .token.class-name { color: #e76f51; }
.token.regex, .token.important, .token.variable { color: #b58900; }
.token.important, .token.bold { font-weight: 700; }
.token.italic { font-style: italic; }

/* Copy button
   ----------------------------------------------------------------------- */
.code-wrap { position: relative; }
.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.32rem 0.65rem;
  font-size: 0.78rem;
  font-weight: 500;
  background: rgba(255, 255, 255, 0.85);
  border: 1px solid var(--color-code-border);
  border-radius: 6px;
  color: var(--color-text-muted);
  cursor: pointer;
  opacity: 0;
  transition: opacity var(--t), background var(--t), color var(--t), transform var(--t);
}
.code-wrap:hover .copy-btn, .copy-btn:focus { opacity: 1; }
.copy-btn:hover { background: var(--color-primary); color: #fff; border-color: var(--color-primary); transform: translateY(-1px); }
.copy-btn.copied { background: var(--color-accent); color: #fff; border-color: var(--color-accent); opacity: 1; }
.copy-btn svg { width: 13px; height: 13px; }

/* Tables
   ----------------------------------------------------------------------- */
.prose .table-wrap { overflow-x: auto; margin: 1.5rem 0; border-radius: var(--radius); border: 1px solid var(--color-border); box-shadow: var(--shadow-sm); }
.prose table { width: 100%; border-collapse: collapse; font-size: 0.95rem; min-width: 480px; }
.prose th, .prose td { padding: 0.7rem 0.9rem; text-align: left; border-bottom: 1px solid var(--color-border); }
.prose thead th { background: var(--color-primary-100); color: var(--color-primary-700); font-weight: 600; }
.prose tbody tr:nth-child(even) { background: var(--color-surface-2); }
.prose tbody tr:hover { background: var(--color-accent-100); }

/* Task lists (checkboxes)
   ----------------------------------------------------------------------- */
.prose .task-list-item,
.prose li.task-list-item {
  list-style: none;
  margin-left: -1.4rem;
  padding-left: 0.2rem;
}
.prose ul:has(> li.task-list-item) { list-style: none; padding-left: 0.3rem; }
.prose .task-list-item-checkbox,
.prose li.task-list-item > input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 1.05em;
  height: 1.05em;
  border: 1.5px solid var(--color-primary);
  border-radius: 4px;
  background: #fff;
  margin-right: 0.55rem;
  vertical-align: -2px;
  cursor: pointer;
  position: relative;
  transition: background var(--t), border-color var(--t);
}
.prose .task-list-item-checkbox:checked,
.prose li.task-list-item > input[type="checkbox"]:checked {
  background: var(--color-accent);
  border-color: var(--color-accent);
}
.prose .task-list-item-checkbox:checked::after,
.prose li.task-list-item > input[type="checkbox"]:checked::after {
  content: "";
  position: absolute;
  left: 3px;
  top: 0px;
  width: 5px;
  height: 9px;
  border: solid #fff;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}
.prose li.task-list-item.checked,
.prose li.task-list-item:has(> input[type="checkbox"]:checked) {
  text-decoration: line-through;
  color: var(--color-text-muted);
}

/* FAQ accordions
   ----------------------------------------------------------------------- */
.faq-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  margin: 0.6rem 0;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--t);
}
.faq-item[open] { box-shadow: var(--shadow-md); }
.faq-item summary {
  list-style: none;
  cursor: pointer;
  padding: 0.9rem 1.1rem;
  font-weight: 600;
  color: var(--color-primary-700);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  user-select: none;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  margin-left: auto;
  font-size: 1.4rem;
  color: var(--color-accent);
  transition: transform var(--t);
}
.faq-item[open] summary::after { content: "−"; transform: rotate(0); }
.faq-item summary:hover { color: var(--color-primary); }
.faq-body { padding: 0 1.1rem 1rem; color: var(--color-text); }

/* Headings: anchor link styling (from markdown-it-anchor headerLink) */
.prose h2 a, .prose h3 a, .prose h4 a, .prose h5 a, .prose h6 a {
  color: inherit;
  text-decoration: none;
  transition: color var(--t);
}
.prose h2 a:hover, .prose h3 a:hover, .prose h4 a:hover, .prose h5 a:hover, .prose h6 a:hover {
  color: var(--color-accent);
}
.prose h2 a:hover::after,
.prose h3 a:hover::after { content: " ¶"; opacity: 0.5; font-weight: 400; }

/* KaTeX
   ----------------------------------------------------------------------- */
.katex { font-size: 1.05em; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.5rem 0; }

/* Mermaid
   ----------------------------------------------------------------------- */
.mermaid {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1rem;
  text-align: center;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-sm);
  overflow-x: auto;
}

/* Footer
   ----------------------------------------------------------------------- */
.site-footer {
  background: linear-gradient(180deg, #f3f7fb 0%, #e9f0f6 100%);
  border-top: 1px solid var(--color-border);
  padding: 2.5rem 0 1.25rem;
  margin-top: 3rem;
}
.footer-inner {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 2rem;
  align-items: start;
}
@media (max-width: 720px) { .footer-inner { grid-template-columns: 1fr; } }
.footer-brand { display: flex; gap: 0.85rem; align-items: flex-start; }
.footer-brand strong { font-size: 1.05rem; color: var(--color-primary-700); }
.footer-brand p { margin: 0.3rem 0 0; font-size: 0.9rem; }
.footer-nav h2 { font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--color-text-muted); margin: 0 0 0.65rem; }
.footer-nav ul { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: 1fr 1fr; gap: 0.3rem 1rem; }
.footer-nav a { text-decoration: none; color: var(--color-text); padding: 0.25rem 0; display: inline-block; transition: color var(--t), transform var(--t); }
.footer-nav a:hover { color: var(--color-primary); transform: translateX(2px); }
.footer-meta { margin-top: 1.5rem; padding-top: 1rem; border-top: 1px solid var(--color-border); color: var(--color-text-muted); }
.muted { color: var(--color-text-muted); }

/* Mobile menu open state from JS */
.site-nav.open { display: block !important; }

/* Wider screens — let text breathe */
@media (min-width: 1440px) {
  :root { --max-w: 1440px; }
}
@media (min-width: 1800px) {
  :root { --max-w: 1560px; }
  body { font-size: 17px; }
}

/* Print
   ----------------------------------------------------------------------- */
@media print {
  .site-header, .site-footer, .article-aside, .breadcrumbs, .copy-btn { display: none; }
  .prose a { color: inherit; text-decoration: none; }
}