/* ==========================================================================
   DSR Pipeline Engineering — Bold Berry light theme
   ========================================================================== */

:root {
  /* Brand palette */
  --berry: #9b1b5a;
  --berry-bright: #c42a77;
  --berry-deep: #6e1244;
  --plum: #5e2a86;
  --teal: #0e7c8c;
  --gold: #d98a2b;
  --rose: #e26fa0;

  /* Surfaces */
  --bg: #fcf8fb;
  --bg-alt: #f6edf3;
  --surface: #ffffff;
  --surface-tint: #fbf3f8;

  /* Text */
  --ink: #2b2230;
  --ink-soft: #483d50;
  --muted: #76697e;

  /* Lines / code */
  --line: #ecdde8;
  --line-strong: #e1ccdb;
  --code-bg: #f8f0f6;
  --code-border: #ecdbe7;

  /* Effects */
  --shadow-sm: 0 1px 2px rgba(67, 17, 44, 0.06), 0 1px 3px rgba(67, 17, 44, 0.08);
  --shadow-md: 0 6px 18px rgba(86, 20, 56, 0.10);
  --shadow-lg: 0 18px 48px rgba(86, 20, 56, 0.16);
  --ring: 0 0 0 3px rgba(196, 42, 119, 0.35);

  --grad-berry: linear-gradient(135deg, #c42a77 0%, #9b1b5a 52%, #5e2a86 100%);
  --grad-berry-soft: linear-gradient(135deg, #fbeef5 0%, #f3e7f4 100%);

  /* Layout */
  --maxw: 1280px;
  /* Content shares the header/footer width so page edges line up. */
  --readw: var(--maxw);
  --header-h: 66px;
  --radius: 14px;
  --radius-sm: 10px;
  --radius-lg: 22px;

  --space: clamp(1rem, 0.6rem + 1.6vw, 2rem);

  --font-sans: "Inter", "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", "Cascadia Code", Consolas, "Liberation Mono", Menlo, monospace;
}

/* ----- Reset ----- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1rem);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: clamp(1rem, 0.97rem + 0.15vw, 1.075rem);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img, svg { max-width: 100%; }
img { height: auto; }

main { flex: 1 0 auto; }

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

h1, h2, h3, h4 {
  line-height: 1.22;
  color: var(--ink);
  font-weight: 700;
  letter-spacing: -0.01em;
}

:focus-visible {
  outline: none;
  box-shadow: var(--ring);
  border-radius: 6px;
}

.skip-link {
  position: absolute;
  left: 0.75rem;
  top: -3rem;
  background: var(--berry);
  color: #fff;
  padding: 0.6rem 1rem;
  border-radius: 0 0 10px 10px;
  z-index: 200;
  transition: top 0.18s ease;
}
.skip-link:focus { top: 0; }

/* ==========================================================================
   Header
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(252, 248, 251, 0.82);
  backdrop-filter: saturate(160%) blur(12px);
  -webkit-backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--line);
  transition: box-shadow 0.2s ease, background 0.2s ease;
}
.site-header.scrolled {
  box-shadow: var(--shadow-md);
  background: rgba(252, 248, 251, 0.92);
}

.header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  min-height: var(--header-h);
  padding: 0 clamp(1rem, 0.5rem + 2vw, 2rem);
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--ink);
  font-weight: 700;
  margin-right: auto;
  border-radius: 12px;
  padding: 4px 6px;
}
.brand-mark {
  border-radius: 9px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.25s ease;
}
.brand:hover .brand-mark { transform: rotate(-4deg) scale(1.05); }
.brand-text { display: flex; flex-direction: column; line-height: 1.05; }
.brand-name {
  font-size: 1.05rem;
  background: var(--grad-berry);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.brand-sub {
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 600;
}

.primary-nav ul {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.35rem;
  margin: 0;
  padding: 0;
}
.nav-link {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.5rem 0.8rem;
  border-radius: 10px;
  color: var(--ink-soft);
  font-weight: 600;
  font-size: 0.94rem;
  line-height: 1.1;
  position: relative;
  transition: color 0.18s ease, background 0.18s ease, transform 0.18s ease;
}
.nav-icon { color: var(--berry); flex: none; transition: transform 0.18s ease; }
.nav-link:hover { background: var(--surface-tint); color: var(--berry-deep); }
.nav-link:hover .nav-icon { transform: translateY(-1px) scale(1.08); }
.nav-link.is-active { color: var(--berry-deep); background: var(--surface); box-shadow: var(--shadow-sm); }
.nav-link.is-active::after {
  content: "";
  position: absolute;
  left: 0.8rem;
  right: 0.8rem;
  bottom: -1px;
  height: 2px;
  border-radius: 2px;
  background: var(--grad-berry);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 40px;
  padding: 0 9px;
  border: 1px solid var(--line-strong);
  border-radius: 10px;
  background: var(--surface);
  cursor: pointer;
}
.nav-toggle-bar {
  height: 2px;
  width: 100%;
  background: var(--berry-deep);
  border-radius: 2px;
  transition: transform 0.22s ease, opacity 0.22s ease;
}
.site-header.nav-open .nav-toggle-bar:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.site-header.nav-open .nav-toggle-bar:nth-child(2) { opacity: 0; }
.site-header.nav-open .nav-toggle-bar:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  flex-shrink: 0;
  margin-top: 4rem;
  background: linear-gradient(180deg, var(--bg-alt), #f1e3ec);
  border-top: 1px solid var(--line);
}
.footer-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 2.6rem clamp(1rem, 0.5rem + 2vw, 2rem) 1.4rem;
  display: flex;
  flex-wrap: wrap;
  gap: 2rem 3rem;
  align-items: flex-start;
}
.footer-brand { display: flex; gap: 0.9rem; align-items: center; max-width: 420px; }
.footer-brand img { border-radius: 10px; box-shadow: var(--shadow-sm); }
.footer-name { margin: 0; font-weight: 700; color: var(--ink); }
.footer-tag { margin: 0.15rem 0 0; color: var(--muted); font-size: 0.92rem; }
.footer-heading {
  margin: 0 0 0.6rem;
  font-size: 0.74rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 700;
}
.footer-nav ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.45rem; }
.footer-nav a {
  color: var(--ink-soft);
  font-weight: 500;
  transition: color 0.16s ease, padding-left 0.16s ease;
}
.footer-nav a:hover { color: var(--berry); padding-left: 4px; }
.footer-bottom {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 1rem clamp(1rem, 0.5rem + 2vw, 2rem) 2rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.88rem;
}
.footer-bottom p { margin: 0; }

/* ==========================================================================
   Hero
   ========================================================================== */
.hero {
  position: relative;
  background: var(--grad-berry-soft);
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}
.hero::before,
.hero::after {
  content: "";
  position: absolute;
  border-radius: 50%;
  filter: blur(8px);
  opacity: 0.5;
  pointer-events: none;
}
.hero::before {
  width: 420px; height: 420px;
  top: -180px; right: -120px;
  background: radial-gradient(circle, rgba(226,111,160,0.30), transparent 70%);
}
.hero::after {
  width: 360px; height: 360px;
  bottom: -160px; left: -120px;
  background: radial-gradient(circle, rgba(94,42,134,0.22), transparent 70%);
}
.hero-inner {
  position: relative;
  max-width: var(--readw);
  margin: 0 auto;
  padding: clamp(2.4rem, 1.5rem + 4vw, 4.5rem) clamp(1rem, 0.5rem + 2vw, 2rem) clamp(2.6rem, 2rem + 3vw, 4rem);
  text-align: center;
}
.hero-logo { margin: 0 auto 1.4rem; }
.hero-logo img {
  width: clamp(108px, 9vw + 70px, 156px);
  height: auto;
  filter: drop-shadow(0 14px 30px rgba(110, 18, 68, 0.28));
  animation: floaty 7s ease-in-out infinite;
}
@keyframes floaty {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}
.hero-title {
  font-size: clamp(2.1rem, 1.4rem + 3.4vw, 3.6rem);
  margin: 0 0 0.5rem;
  background: var(--grad-berry);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero-tagline {
  margin: 0 auto 1.6rem;
  font-size: clamp(1.05rem, 0.95rem + 0.6vw, 1.3rem);
  color: var(--berry-deep);
  font-weight: 600;
  max-width: 42ch;
}
.hero-lead {
  margin: 0 auto 1.1rem;
  max-width: 76ch;
  color: var(--ink-soft);
}

.hero-cta {
  margin-top: 2rem;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  text-align: left;
}
.cta {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  padding: 1rem 1.1rem;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.cta:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--line-strong); }
.cta-icon {
  flex: none;
  display: grid;
  place-items: center;
  width: 46px; height: 46px;
  border-radius: 12px;
  color: #fff;
}
.cta-1 .cta-icon { background: linear-gradient(135deg, #c42a77, #9b1b5a); }
.cta-2 .cta-icon { background: linear-gradient(135deg, #1aa3a0, #0e7c8c); }
.cta-3 .cta-icon { background: linear-gradient(135deg, #7b46b8, #5e2a86); }
.cta-svg { width: 24px; height: 24px; }
.cta-text { display: flex; flex-direction: column; min-width: 0; }
.cta-label { font-weight: 700; line-height: 1.25; }
.cta-go {
  display: inline-flex; align-items: center; gap: 0.3rem;
  color: var(--berry); font-size: 0.88rem; font-weight: 600;
}
.cta-arrow { transition: transform 0.2s ease; }
.cta:hover .cta-arrow { transform: translateX(4px); }

/* ==========================================================================
   Home sections
   ========================================================================== */
.home-section { padding: clamp(2.4rem, 1.6rem + 3vw, 4rem) 0; }
.home-section.alt { background: var(--bg-alt); border-block: 1px solid var(--line); }
.home-section-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 clamp(1rem, 0.5rem + 2vw, 2rem);
}
.section-title {
  font-size: clamp(1.5rem, 1.2rem + 1.4vw, 2.1rem);
  margin: 0 0 0.5rem;
  color: var(--berry-deep);
}
.section-intro { margin: 0 0 1.8rem; max-width: 70ch; color: var(--ink-soft); }

/* Mermaid */
.mermaid {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  overflow-x: auto;
  text-align: center;
  font-family: var(--font-sans);
}
.mermaid:not([data-processed]) { color: var(--muted); font-family: var(--font-mono); white-space: pre; }

/* Cards */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: 1.4rem;
}
.card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
  transition: transform 0.22s ease, box-shadow 0.22s ease;
}
.card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 4px;
}
.card-1::before { background: linear-gradient(90deg, #c42a77, #9b1b5a); }
.card-2::before { background: linear-gradient(90deg, #1aa3a0, #0e7c8c); }
.card-3::before { background: linear-gradient(90deg, #7b46b8, #5e2a86); }
.card:hover { transform: translateY(-5px); box-shadow: var(--shadow-lg); }
.card-head { display: flex; align-items: center; gap: 0.8rem; color: var(--ink); }
.card-icon {
  flex: none; display: grid; place-items: center;
  width: 44px; height: 44px; border-radius: 12px; color: #fff;
}
.card-1 .card-icon { background: linear-gradient(135deg, #c42a77, #9b1b5a); }
.card-2 .card-icon { background: linear-gradient(135deg, #1aa3a0, #0e7c8c); }
.card-3 .card-icon { background: linear-gradient(135deg, #7b46b8, #5e2a86); }
.card-svg { width: 23px; height: 23px; }
.card-title { font-size: 1.12rem; margin: 0; }
.card-head:hover .card-title { color: var(--berry); }
.card-desc { color: var(--muted); font-size: 0.95rem; margin: 0.9rem 0 1rem; }
.card-links { list-style: none; margin: 0 0 1rem; padding: 0; display: grid; gap: 0.35rem; }
.card-links a {
  display: inline-flex; align-items: center; gap: 0.35rem;
  color: var(--ink-soft); font-weight: 500; font-size: 0.94rem;
  transition: color 0.16s ease, transform 0.16s ease;
}
.card-links a:hover { color: var(--berry); transform: translateX(3px); }
.card-chevron { color: var(--rose); flex: none; }
.card-more {
  margin-top: auto;
  display: inline-flex; align-items: center; gap: 0.4rem;
  font-weight: 700; color: var(--berry);
}
.card-more-arrow { transition: transform 0.2s ease; }
.card-more:hover .card-more-arrow { transform: translateX(4px); }

/* Audience */
.audience-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.4rem;
}
.audience-item {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.4rem;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.audience-item:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.audience-icon {
  display: grid; place-items: center;
  width: 46px; height: 46px; border-radius: 12px;
  background: var(--grad-berry-soft); color: var(--berry);
  margin-bottom: 0.8rem;
}
.aud-svg { width: 24px; height: 24px; }
.audience-item h3 { margin: 0 0 0.4rem; font-size: 1.08rem; color: var(--berry-deep); }
.audience-item p { margin: 0; color: var(--muted); font-size: 0.95rem; }

/* ==========================================================================
   Page / article layout
   ========================================================================== */
.page-wrap {
  max-width: var(--readw);
  margin: 0 auto;
  padding: clamp(1.4rem, 1rem + 2vw, 2.6rem) clamp(1rem, 0.5rem + 2vw, 2rem) 1rem;
}

/* Breadcrumbs */
.breadcrumbs ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.15rem 0.4rem;
  margin: 0 0 1.4rem;
  padding: 0;
  font-size: 0.88rem;
}
.crumb { display: inline-flex; align-items: center; gap: 0.4rem; color: var(--muted); }
.crumb a { color: var(--muted); font-weight: 500; transition: color 0.16s ease; }
.crumb a:hover { color: var(--berry); }
.crumb [aria-current="page"] { color: var(--berry-deep); font-weight: 600; }
.crumb-sep { display: inline-flex; color: var(--line-strong); }
.crumb-chevron { width: 14px; height: 14px; }

/* ==========================================================================
   Prose
   ========================================================================== */
.prose { color: var(--ink-soft); }
.prose > :first-child { margin-top: 0; }

.prose h1 {
  font-size: clamp(1.8rem, 1.4rem + 2vw, 2.7rem);
  margin: 0 0 1.1rem;
  color: var(--ink);
  background: var(--grad-berry);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.prose h2 {
  font-size: clamp(1.35rem, 1.15rem + 1vw, 1.85rem);
  margin: 2.4rem 0 0.9rem;
  padding-bottom: 0.4rem;
  color: var(--berry-deep);
  border-bottom: 1px solid var(--line);
}
.prose h3 {
  font-size: clamp(1.15rem, 1.05rem + 0.5vw, 1.4rem);
  margin: 1.9rem 0 0.7rem;
  color: var(--plum);
}
.prose h4 { font-size: 1.08rem; margin: 1.5rem 0 0.6rem; color: var(--ink); }

.prose p { margin: 0 0 1.15rem; }
.prose ul, .prose ol { margin: 0 0 1.2rem; padding-left: 1.4rem; }
.prose li { margin: 0.35rem 0; }
.prose li::marker { color: var(--berry); }
.prose strong { color: var(--ink); font-weight: 700; }

.prose blockquote {
  margin: 1.4rem 0;
  padding: 0.6rem 1.2rem;
  border-left: 4px solid var(--berry-bright);
  background: var(--surface-tint);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--ink-soft);
}
.prose blockquote p:last-child { margin-bottom: 0; }
.prose hr { border: none; border-top: 1px solid var(--line); margin: 2.2rem 0; }

/* Prose links */
.prose a {
  color: var(--berry);
  font-weight: 500;
  text-decoration: underline;
  text-decoration-color: rgba(196, 42, 119, 0.32);
  text-underline-offset: 0.18em;
  text-decoration-thickness: 1.5px;
  transition: color 0.16s ease, text-decoration-color 0.16s ease, background 0.16s ease;
  border-radius: 3px;
}
.prose a:hover {
  color: var(--berry-deep);
  text-decoration-color: var(--berry);
  background: rgba(196, 42, 119, 0.07);
}

/* Heading anchors */
.heading-anchor {
  margin-left: 0.4rem;
  color: var(--rose);
  text-decoration: none;
  opacity: 0;
  font-weight: 600;
  transition: opacity 0.16s ease;
}
h2:hover .heading-anchor,
h3:hover .heading-anchor,
h4:hover .heading-anchor { opacity: 1; }

/* ==========================================================================
   Code
   ========================================================================== */
:not(pre) > code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--code-bg);
  color: var(--berry-deep);
  padding: 0.12em 0.4em;
  border-radius: 6px;
  word-break: break-word;
}

.code-block, pre[class*="language-"] {
  position: relative;
}
pre[class*="language-"] {
  margin: 1.3rem 0;
  padding: 1.1rem 1.2rem;
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  overflow-x: auto;
  font-size: 0.9rem;
  line-height: 1.6;
  -webkit-overflow-scrolling: touch;
  tab-size: 4;
}
pre[class*="language-"] code {
  font-family: var(--font-mono);
  background: none;
  color: var(--ink);
  padding: 0;
  font-size: inherit;
}

/* Copy button */
.copy-btn {
  position: absolute;
  top: 0.55rem;
  right: 0.55rem;
  display: inline-flex;
  align-items: center;
  gap: 0.32rem;
  padding: 0.32rem 0.6rem;
  font-family: var(--font-sans);
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--berry-deep);
  background: rgba(255, 255, 255, 0.85);
  border: 1px solid var(--code-border);
  border-radius: 8px;
  cursor: pointer;
  opacity: 0;
  transform: translateY(-2px);
  transition: opacity 0.16s ease, transform 0.16s ease, background 0.16s ease, color 0.16s ease;
}
pre[class*="language-"]:hover .copy-btn,
.copy-btn:focus-visible { opacity: 1; transform: translateY(0); }
.copy-btn:hover { background: #fff; color: var(--berry); }
.copy-btn.copied { color: var(--teal); border-color: rgba(14, 124, 140, 0.4); }
.copy-btn svg { width: 14px; height: 14px; }

/* Prism token colors — light berry theme */
.token.comment, .token.prolog, .token.doctype, .token.cdata { color: #978ba0; font-style: italic; }
.token.punctuation { color: #6e6178; }
.token.namespace { opacity: 0.7; }
.token.keyword, .token.boolean, .token.important { color: var(--berry); font-weight: 600; }
.token.tag, .token.property, .token.constant, .token.symbol, .token.attr-name { color: #a51e63; }
.token.selector, .token.string, .token.char, .token.attr-value, .token.inserted { color: #2e7d5b; }
.token.number, .token.unit { color: #b0552a; }
.token.function, .token.class-name { color: #6a2e9e; }
.token.builtin, .token.regex { color: var(--teal); }
.token.operator, .token.entity, .token.url { color: #7a5a86; }
.token.decorator, .token.annotation { color: #b0552a; }
.token.deleted { color: #c0392b; }

/* ==========================================================================
   Tables
   ========================================================================== */
.table-wrap {
  margin: 1.4rem 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  background: var(--surface);
}
.table-wrap table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.94rem;
  min-width: 32rem;
}
.table-wrap th, .table-wrap td {
  padding: 0.7rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
.table-wrap thead th {
  background: var(--surface-tint);
  color: var(--berry-deep);
  font-weight: 700;
  white-space: nowrap;
  border-bottom: 2px solid var(--line-strong);
}
.table-wrap tbody tr:last-child td { border-bottom: none; }
.table-wrap tbody tr:hover { background: var(--surface-tint); }

/* ==========================================================================
   Task lists (togglable checkboxes)
   ========================================================================== */
.prose ul:has(> .task-list-item) { list-style: none; padding-left: 0.2rem; }
.task-list-item { list-style: none; display: flex; align-items: flex-start; gap: 0.6rem; }
.task-list-item::marker { content: ""; }
.task-list-item-checkbox,
.task-list-item input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  flex: none;
  width: 1.2em; height: 1.2em;
  margin-top: 0.22em;
  border: 2px solid var(--line-strong);
  border-radius: 6px;
  background: var(--surface);
  cursor: pointer;
  display: grid;
  place-content: center;
  transition: background 0.16s ease, border-color 0.16s ease;
}
.task-list-item input[type="checkbox"]::before {
  content: "";
  width: 0.62em; height: 0.62em;
  transform: scale(0);
  transform-origin: center;
  transition: transform 0.14s ease;
  box-shadow: inset 1em 1em #fff;
  clip-path: polygon(14% 44%, 0 65%, 50% 100%, 100% 16%, 80% 0%, 43% 62%);
}
.task-list-item input[type="checkbox"]:checked {
  background: var(--grad-berry);
  border-color: var(--berry);
}
.task-list-item input[type="checkbox"]:checked::before { transform: scale(1); }
.task-list-item.is-checked { color: var(--muted); text-decoration: line-through; text-decoration-color: var(--line-strong); }
.task-list-item.is-checked .task-list-item-label { color: var(--muted); }

/* ==========================================================================
   FAQ accordions
   ========================================================================== */
.faq { margin: 1.6rem 0; display: grid; gap: 0.7rem; }
.faq details {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}
.faq summary {
  cursor: pointer;
  list-style: none;
  padding: 0.95rem 1.1rem;
  font-weight: 600;
  color: var(--berry-deep);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "";
  width: 10px; height: 10px;
  border-right: 2px solid var(--berry);
  border-bottom: 2px solid var(--berry);
  transform: rotate(45deg);
  transition: transform 0.2s ease;
  flex: none;
}
.faq details[open] summary::after { transform: rotate(-135deg); }
.faq summary:hover { background: var(--surface-tint); }
.faq .faq-body { padding: 0 1.1rem 1.1rem; color: var(--ink-soft); }
.faq .faq-body > :first-child { margin-top: 0; }
.faq .faq-body > :last-child { margin-bottom: 0; }

/* KaTeX */
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.4rem 0; }

/* ==========================================================================
   Related content
   ========================================================================== */
.related {
  max-width: var(--readw);
  margin: 2.6rem auto 0;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}
.related-heading { font-size: 1.25rem; color: var(--berry-deep); margin: 0 0 1.1rem; }
.related-grid {
  list-style: none; margin: 0; padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}
.related-card {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  height: 100%;
  padding: 1.1rem 1.2rem;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  color: var(--ink);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.related-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--line-strong); }
.related-card-title { font-weight: 700; color: var(--berry-deep); }
.related-card-desc { font-size: 0.9rem; color: var(--muted); line-height: 1.55; }
.related-card-go { margin-top: auto; color: var(--berry); }
.related-arrow { transition: transform 0.2s ease; }
.related-card:hover .related-arrow { transform: translateX(4px); }

.related-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.5rem; }
.related-list a {
  display: inline-flex; align-items: center; gap: 0.5rem;
  color: var(--ink-soft); font-weight: 500;
  transition: color 0.16s ease, transform 0.16s ease;
}
.related-list a:hover { color: var(--berry); transform: translateX(3px); }
.related-doc { color: var(--rose); flex: none; }
.related-back { margin-top: 1.4rem; }
.related-back a {
  display: inline-flex; align-items: center; gap: 0.45rem;
  font-weight: 600; color: var(--berry);
}
.back-arrow { transform: rotate(180deg); transition: transform 0.2s ease; }
.related-back a:hover .back-arrow { transform: rotate(180deg) translateX(4px); }

/* ==========================================================================
   Buttons / 404
   ========================================================================== */
.btn-primary, .btn-ghost {
  display: inline-flex; align-items: center; gap: 0.45rem;
  padding: 0.65rem 1.1rem; border-radius: 10px; font-weight: 600;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}
.btn-primary { background: var(--grad-berry); color: #fff; box-shadow: var(--shadow-md); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }
.btn-ghost { background: var(--surface); color: var(--berry-deep); border: 1px solid var(--line); }
.btn-ghost:hover { transform: translateY(-2px); box-shadow: var(--shadow-sm); border-color: var(--line-strong); }
.btn-icon { flex: none; }

.notfound { max-width: 60ch; margin: 2rem auto 4rem; text-align: center; }
.notfound-code {
  font-size: clamp(4rem, 10vw, 7rem); font-weight: 800; margin: 0; line-height: 1;
  background: var(--grad-berry); -webkit-background-clip: text; background-clip: text; color: transparent;
}
.notfound-title { font-size: 1.6rem; margin: 0.4rem 0 0.8rem; color: var(--berry-deep); }
.notfound-text { color: var(--muted); margin: 0 0 1.6rem; }
.notfound-links { display: flex; flex-wrap: wrap; gap: 0.7rem; justify-content: center; }

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 860px) {
  .nav-toggle { display: flex; }
  .primary-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: rgba(252, 248, 251, 0.98);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow-md);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.28s ease;
  }
  .site-header.nav-open .primary-nav { max-height: 70vh; }
  .primary-nav ul {
    flex-direction: column;
    align-items: stretch;
    gap: 0.2rem;
    padding: 0.7rem clamp(1rem, 0.5rem + 2vw, 2rem) 1rem;
  }
  .nav-link { padding: 0.7rem 0.8rem; font-size: 1rem; }
  .nav-link.is-active::after { display: none; }
  .nav-link.is-active { background: var(--surface-tint); }
}

@media (max-width: 720px) {
  .hero-cta { grid-template-columns: 1fr; }
  .footer-inner { gap: 1.6rem; }
}

@media (min-width: 1500px) {
  :root { --maxw: 1380px; }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; scroll-behavior: auto !important; }
}