/* minAction.net — minimal academic theme.
 * System fonts (no Google Fonts → fast first paint, GDPR-clean).
 * Single-column reading layout, max 720px for prose. */

:root {
  --bg:        #ffffff;
  --fg:        #1a1a1a;
  --muted:     #6a6a6a;
  --border:    #e3e3e3;
  --link:      #0b5fbe;
  --link-hov:  #073b78;
  --accent:    #1a5f3f;
  --code-bg:   #f5f5f5;
  --max-w:     720px;
  --max-w-wide: 960px;
  --radius:    4px;
  --serif:     Georgia, Cambria, "Times New Roman", Times, serif;
  --sans:      -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  --mono:      ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.6;
  color: var(--fg);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Header ---------- */
.site-header {
  border-bottom: 1px solid var(--border);
  padding: 18px 0;
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(6px);
  z-index: 50;
}
.site-header .container { max-width: var(--max-w-wide); }
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
}
.brand {
  font-weight: 600;
  font-size: 1.1rem;
  text-decoration: none;
  color: var(--fg);
  letter-spacing: -0.01em;
}
.brand-name { color: var(--fg); }
.brand-dot  { color: var(--accent); }
.brand-tld  { color: var(--muted); }

.site-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 22px;
  flex-wrap: wrap;
}
.site-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.97rem;
  border-bottom: 2px solid transparent;
  padding-bottom: 2px;
}
.site-nav a:hover { color: var(--fg); }
.site-nav a.active {
  color: var(--fg);
  border-bottom-color: var(--accent);
}

/* ---------- Main content ---------- */
main.container {
  padding-top: 40px;
  padding-bottom: 80px;
}

h1.page-title {
  font-size: 2rem;
  line-height: 1.2;
  margin: 0 0 0.4em 0;
  letter-spacing: -0.015em;
}
.lead {
  font-size: 1.18rem;
  color: var(--muted);
  margin: 0 0 2em 0;
  line-height: 1.5;
}
h2 {
  font-size: 1.4rem;
  margin: 2em 0 0.6em 0;
  letter-spacing: -0.01em;
}
h3 {
  font-size: 1.1rem;
  margin: 1.6em 0 0.4em 0;
  color: var(--fg);
}

p, ul, ol, blockquote { margin: 0 0 1em 0; }

a { color: var(--link); text-decoration: none; }
a:hover { color: var(--link-hov); text-decoration: underline; }

ul, ol { padding-left: 1.4em; }
li { margin-bottom: 0.3em; }

blockquote {
  border-left: 3px solid var(--border);
  padding: 0.4em 1em;
  color: var(--muted);
  font-style: italic;
  margin: 1.2em 0;
}

code {
  font-family: var(--mono);
  font-size: 0.9em;
  background: var(--code-bg);
  padding: 0.1em 0.35em;
  border-radius: var(--radius);
}
pre {
  background: var(--code-bg);
  padding: 14px 16px;
  border-radius: var(--radius);
  overflow-x: auto;
  font-size: 0.88em;
  line-height: 1.5;
}
pre code {
  background: transparent;
  padding: 0;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 1.5em auto;
  border-radius: var(--radius);
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.4em 0;
  font-size: 0.95em;
}
th, td {
  text-align: left;
  padding: 0.55em 0.75em;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
th {
  font-weight: 600;
  background: #fafafa;
}

hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 2.5em 0;
}

/* ---------- Validation grid (Home) ---------- */
.domain-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
  margin: 1.5em 0;
}
.domain-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s, transform 0.15s;
}
.domain-card:hover {
  border-color: var(--accent);
  text-decoration: none;
  transform: translateY(-2px);
}
.domain-card h3 {
  margin: 0 0 6px 0;
  color: var(--accent);
}
.domain-card .paper-ref {
  display: block;
  font-size: 0.85em;
  color: var(--muted);
  margin-top: 8px;
}

/* ---------- Validation footer cross-links ---------- */
.see-also {
  margin-top: 3em;
  padding: 18px 22px;
  background: #fafafa;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.see-also h3 {
  margin-top: 0;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}
.see-also ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

/* ---------- KaTeX block equations ---------- */
.katex-display {
  margin: 1.4em 0;
  overflow-x: auto;
  overflow-y: hidden;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 28px 0 36px;
  margin-top: 48px;
  font-size: 0.92rem;
  color: var(--muted);
}
.footer-inner p { margin: 0 0 0.4em 0; }
.muted { color: var(--muted); }

/* ---------- Responsive ---------- */
@media (max-width: 600px) {
  body { font-size: 16px; }
  h1.page-title { font-size: 1.6rem; }
  .lead { font-size: 1.05rem; }
  .header-inner { gap: 12px; }
  .site-nav ul { gap: 14px; }
  .site-nav a { font-size: 0.92rem; }
}