/* ============================================================
   QUALIFIER — Design System
   Aesthetic: Inspector's logbook. Blueprint precision.
   Dark, authoritative, utilitarian.
   ============================================================ */

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

:root {
  /* --- Palette --- */
  --void: #0c0e11;
  --slab: #141720;
  --plate: #1b1f2a;
  --ridge: #252a38;
  --steel: #3a4158;
  --flint: #6b7394;
  --ash: #9ba3bf;
  --chalk: #d0d5e3;
  --white: #eef0f6;

  /* Signal colors */
  --pass: #34d399;
  --pass-dim: #34d39920;
  --warn: #fbbf24;
  --warn-dim: #fbbf2420;
  --fail: #f87171;
  --fail-dim: #f8717120;
  --info: #60a5fa;
  --info-dim: #60a5fa20;

  /* Accent */
  --accent: #818cf8;
  --accent-dim: #818cf815;
  --accent-mid: #818cf840;

  /* Typography */
  --display: "Instrument Sans", "Inter", "Helvetica Neue", sans-serif;
  --body:
    "Atkinson Hyperlegible Next", "Atkinson Hyperlegible", system-ui, sans-serif;
  --mono: "JetBrains Mono", "SF Mono", "Consolas", monospace;

  /* Grid paper pattern */
  --grid-line: #ffffff06;
  --grid-line-major: #ffffff0a;
}

html {
  font-size: 16px;
  line-height: 1.6;
  color: var(--chalk);
  background: var(--void);
}

body {
  font-family: var(--body);
  max-width: 68rem;
  margin: 0 auto;
  padding: 0 1.5rem;
  background-image:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 24px 24px;
  background-position: -1px -1px;
}

/* --- Typography --- */
h1 {
  font-family: var(--display);
  font-weight: 700;
  font-size: 1.5rem;
  line-height: 1.2;
  color: var(--white);
  margin: 2.5rem 0 1rem;
  letter-spacing: -0.01em;
}
h2 {
  font-family: var(--display);
  font-weight: 600;
  font-size: 1.15rem;
  line-height: 1.3;
  color: var(--white);
  margin: 2.5rem 0 0.6rem;
  letter-spacing: -0.005em;
  border-bottom: 1px solid var(--ridge);
  padding-bottom: 0.4rem;
}
h3 {
  font-family: var(--display);
  font-weight: 600;
  font-size: 0.95rem;
  line-height: 1.3;
  color: var(--ash);
  margin: 1.5rem 0 0.4rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 0.82rem;
}
h4 {
  font-family: var(--mono);
  font-weight: 600;
  font-size: 0.8rem;
  line-height: 1.3;
  color: var(--flint);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin: 1.25rem 0 0.4rem;
}

p {
  margin: 0.75rem 0;
}
a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s;
}
a:hover {
  color: var(--white);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

ul,
ol {
  margin: 0.75rem 0 0.75rem 1.5rem;
}
li {
  margin: 0.25rem 0;
}
strong {
  font-weight: 600;
  color: var(--white);
}

/* --- Heading anchors --- */
h1 > a.header-anchor,
h2 > a.header-anchor,
h3 > a.header-anchor,
h4 > a.header-anchor {
  color: inherit;
  text-decoration: none;
}
h1 > a.header-anchor:hover,
h2 > a.header-anchor:hover,
h3 > a.header-anchor:hover,
h4 > a.header-anchor:hover {
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
}

/* --- Syntax highlighting (Prism) --- */
.token.property {
  color: #c4b5fd;
}
.token.string,
.token.url {
  color: #6ee7b7;
}
.token.number {
  color: #fcd34d;
}
.token.keyword,
.token.selector {
  color: #f0abfc;
}
.token.function,
.token.class-name {
  color: #93c5fd;
}
.token.operator {
  color: var(--ash);
}
.token.punctuation {
  color: var(--flint);
}
.token.comment {
  color: var(--steel);
  font-style: italic;
}
.token.namespace {
  opacity: 0.7;
}

/* --- Code --- */
code {
  font-family: var(--mono);
  font-size: 0.84em;
  background: var(--plate);
  padding: 0.15em 0.4em;
  border-radius: 3px;
  color: var(--chalk);
  border: 1px solid var(--ridge);
}
pre {
  background: var(--slab);
  border: 1px solid var(--ridge);
  border-left: 3px solid var(--accent-mid);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1rem 0;
  line-height: 1.55;
  border-radius: 2px;
}
pre code {
  background: none;
  padding: 0;
  font-size: 0.82rem;
  border: none;
  border-radius: 0;
}

/* --- Tables --- */
table {
  border-collapse: collapse;
  width: 100%;
  margin: 1rem 0;
  font-size: 0.92rem;
}
th,
td {
  text-align: left;
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--ridge);
}
th {
  font-family: var(--mono);
  font-weight: 600;
  font-size: 0.72rem;
  color: var(--flint);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* --- Navigation --- */
.site-nav {
  display: flex;
  align-items: center;
  gap: 2rem;
  padding: 1rem 0;
  border-bottom: 1px solid var(--ridge);
  font-family: var(--mono);
  font-size: 0.78rem;
}
.nav-logo {
  font-family: var(--display);
  font-weight: 700;
  font-size: 0.9rem;
  text-decoration: none;
  color: var(--white);
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.nav-logo::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  background: var(--accent);
  border-radius: 1px;
  flex-shrink: 0;
}
.nav-links {
  display: flex;
  gap: 1.25rem;
}
.nav-links a {
  font-family: var(--mono);
  font-weight: 500;
  text-decoration: none;
  font-size: 0.75rem;
  color: var(--flint);
  letter-spacing: 0.02em;
  transition: color 0.15s;
}
.nav-links a:hover {
  color: var(--white);
  text-decoration: none;
}
.nav-links a[aria-current] {
  color: var(--accent);
}
.nav-github {
  opacity: 0.5;
}
.nav-github:hover {
  opacity: 1;
}

/* --- Divider --- */
.divider {
  height: 1px;
  background: var(--ridge);
  margin: 0;
  position: relative;
}
.divider::after {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 48px;
  height: 1px;
  background: var(--accent);
}

/* --- Footer --- */
.site-footer {
  margin-top: 4rem;
  padding: 1.5rem 0;
  border-top: 1px solid var(--ridge);
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--steel);
  text-align: center;
  letter-spacing: 0.01em;
}
.site-footer a {
  color: var(--steel);
}
.site-footer a:hover {
  color: var(--accent);
}

/* --- Hero --- */
.hero {
  padding: 4rem 0 3rem;
  border-bottom: none;
  margin-bottom: 0;
  display: flex;
  align-items: flex-start;
  gap: 3rem;
}
.hero-content {
  flex: 1;
  min-width: 0;
}
.hero h1 {
  font-size: 2.8rem;
  margin: 0 0 0.75rem;
  line-height: 1.05;
  letter-spacing: -0.03em;
  color: var(--white);
}
.hero h1 .hero-mark {
  color: var(--accent);
}
.hero .tagline {
  font-family: var(--body);
  font-size: 1.05rem;
  color: var(--ash);
  margin: 0 0 1.75rem;
  max-width: 44rem;
  line-height: 1.6;
}
.hero .tagline strong {
  color: var(--white);
  font-weight: 600;
}
.hero-install {
  font-family: var(--mono);
  font-size: 0.85rem;
  background: var(--slab);
  border: 1px solid var(--ridge);
  border-left: 3px solid var(--accent-mid);
  padding: 0.6rem 1rem;
  display: inline-block;
  border-radius: 2px;
}
.hero-install .prompt {
  color: var(--flint);
  user-select: none;
}
.try-it-btn {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid var(--accent-mid);
  padding: 0.3rem 0.75rem;
  margin-left: 1rem;
  cursor: pointer;
  transition: all 0.15s;
  vertical-align: middle;
  border-radius: 2px;
}
.try-it-btn:hover {
  background: var(--accent);
  color: var(--void);
  border-color: var(--accent);
}
.try-it-btn:disabled {
  opacity: 0.3;
  cursor: default;
}
.hero + .divider {
  margin-bottom: 2rem;
}

/* --- Concept cards --- */
.concepts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
  gap: 1px;
  margin: 1.5rem 0;
  background: var(--ridge);
}
.concept-card {
  background: var(--slab);
  padding: 1.25rem 1.5rem;
}
.concept-card h3 {
  margin: 0 0 0.5rem;
  font-size: 0.78rem;
  color: var(--accent);
  letter-spacing: 0.06em;
}
.concept-card p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--ash);
  line-height: 1.55;
}

/* --- Score bar (inline) --- */
.score-bar {
  font-family: var(--mono);
  font-size: 0.82rem;
  letter-spacing: 0.02em;
}
.score-bar .filled {
  color: var(--pass);
}
.score-bar .empty {
  color: var(--ridge);
}
.score-bar .negative {
  color: var(--fail);
}

/* --- Propagation diagram --- */
.propagation-figure {
  background: var(--slab);
  border: 1px solid var(--ridge);
  padding: 1.5rem 1.5rem 1rem;
  margin: 1.25rem 0;
  overflow-x: auto;
  border-radius: 2px;
}
.propagation-svg {
  display: block;
  width: 100%;
  max-width: 700px;
  height: auto;
  margin: 0 auto;
}

/* --- Subtitle --- */
.subtitle {
  font-family: var(--body);
  font-size: 1rem;
  color: var(--ash);
  margin-bottom: 2rem;
  line-height: 1.6;
}

/* --- Blueprint illustrations --- */
.topo {
  display: block;
  pointer-events: none;
}
.topo-hero {
  width: clamp(200px, 35%, 340px);
  height: auto;
  flex-shrink: 0;
}
.topo-wide {
  width: 100%;
  height: auto;
  margin: 1.5rem 0;
}

/* --- Page title --- */
.page-title {
  margin-top: 2rem;
}

/* --- Kind badge --- */
.kind-badge {
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.15rem 0.5rem;
  display: inline-block;
  border-radius: 2px;
}
.kind-badge.positive {
  background: var(--pass-dim);
  color: var(--pass);
  border: 1px solid #34d39940;
}
.kind-badge.negative {
  background: var(--fail-dim);
  color: var(--fail);
  border: 1px solid #f8717140;
}
.kind-badge.neutral {
  background: var(--accent-dim);
  color: var(--accent);
  border: 1px solid var(--accent-mid);
}

/* --- Spec content --- */
.spec-content h2 {
  margin-top: 3rem;
}
.spec-content h3 {
  margin-top: 2rem;
}

/* --- Responsive --- */
@media (max-width: 640px) {
  html {
    font-size: 15px;
  }
  .hero {
    flex-direction: column;
    padding: 2.5rem 0 2rem;
  }
  .hero h1 {
    font-size: 1.8rem;
  }
  .topo-hero {
    width: 80%;
    max-width: 280px;
  }
  .site-nav {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
  .concepts {
    grid-template-columns: 1fr;
  }
}