/* Invariant Systems — Shared Design System
   T0 (public) stylesheet for all pages */

:root {
  --bg: #fafafa;
  --fg: #1a1a2e;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --muted: #64748b;
  --border: #e2e8f0;
  --code-bg: #f1f5f9;
  --card-bg: #ffffff;
  --max-w: 720px;
  --green: #16a34a;
  --red: #ef4444;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f172a;
    --fg: #e2e8f0;
    --accent: #60a5fa;
    --accent-hover: #93bbfc;
    --muted: #94a3b8;
    --border: #334155;
    --code-bg: #1e293b;
    --card-bg: #1e293b;
    --green: #4ade80;
    --red: #f87171;
  }
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

code {
  font-family: "SF Mono", "Fira Code", "Fira Mono", Menlo, Consolas, monospace;
  background: var(--code-bg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-size: 0.9em;
}

pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25em 1.5em;
  overflow-x: auto;
  font-size: 0.88em;
  line-height: 1.6;
}

pre code { background: none; padding: 0; }

/* Layout */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 1.5em; }

/* Header */
header {
  border-bottom: 1px solid var(--border);
  padding: 1.5em 0;
}

header .container {
  display: flex; align-items: center; justify-content: space-between;
}

header .logo {
  font-size: 1.1em; font-weight: 700; letter-spacing: -0.02em;
  color: var(--fg); text-decoration: none;
}

header .logo:hover { color: var(--fg); text-decoration: none; }

header nav { display: flex; align-items: center; gap: 1.25em; }
header nav a { color: var(--muted); font-size: 0.9em; }
header nav a:hover { color: var(--fg); text-decoration: none; }
header nav a.active { color: var(--fg); font-weight: 600; }

/* Buttons */
.btn {
  display: inline-block; background: var(--accent); color: #fff;
  padding: 0.6em 1.4em; border-radius: 6px; font-weight: 600;
  font-size: 0.9em; transition: background 0.15s; margin: 0.3em;
}

.btn:hover { background: var(--accent-hover); color: #fff; text-decoration: none; }

.btn-outline {
  background: transparent; color: var(--accent); border: 1px solid var(--accent);
}

.btn-outline:hover { background: var(--accent); color: #fff; }

/* Sections */
section { padding: 3em 0; border-top: 1px solid var(--border); }
section:first-of-type { border-top: none; }
section h2 { font-size: 1.4em; font-weight: 700; margin-bottom: 0.8em; letter-spacing: -0.02em; }
section h3 { font-size: 1.1em; font-weight: 600; margin: 1.5em 0 0.5em; }
section p + p { margin-top: 0.8em; }
section ul { list-style: none; padding: 0; }
section ul li { padding: 0.3em 0; padding-left: 1.2em; position: relative; }
section ul li::before { content: "\2022"; color: var(--accent); position: absolute; left: 0; }

/* Cards */
.card-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1em; margin-top: 1em; }
@media (max-width: 600px) { .card-grid { grid-template-columns: 1fr; } }

.card {
  background: var(--card-bg); border: 1px solid var(--border);
  border-radius: 8px; padding: 1.25em;
}

.card h3 { margin: 0 0 0.4em; font-size: 1em; }
.card p { font-size: 0.9em; color: var(--muted); }

/* Stat grid */
.stat-grid {
  display: grid; grid-template-columns: repeat(4, 1fr);
  gap: 1em; margin: 1.5em 0; text-align: center;
}

@media (max-width: 600px) { .stat-grid { grid-template-columns: 1fr 1fr; } }

.stat-grid .num { font-size: 1.8em; font-weight: 800; color: var(--accent); }
.stat-grid .label { font-size: 0.8em; color: var(--muted); text-transform: uppercase; letter-spacing: 0.05em; }

/* Tables */
table { width: 100%; border-collapse: collapse; margin-top: 1em; }
th, td { text-align: left; padding: 0.6em 0.8em; border-bottom: 1px solid var(--border); font-size: 0.9em; }
th { font-weight: 600; color: var(--muted); font-size: 0.8em; text-transform: uppercase; letter-spacing: 0.05em; }

/* Urgency / callout boxes */
.callout {
  background: var(--code-bg);
  border-left: 3px solid var(--accent);
  padding: 1em 1.25em;
  border-radius: 0 8px 8px 0;
  margin: 1.5em 0;
  font-size: 0.95em;
}

.callout.warning { border-left-color: var(--red); }
.callout.warning strong { color: var(--red); }
.callout.success { border-left-color: var(--green); }
.callout.success strong { color: var(--green); }

/* Deploy cards */
.deploy-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 1em; margin-top: 1em;
}

@media (max-width: 600px) { .deploy-grid { grid-template-columns: 1fr; } }

.deploy-card {
  background: var(--card-bg); border: 1px solid var(--border);
  border-radius: 8px; padding: 1.25em;
  border-left: 3px solid var(--accent);
}

.deploy-card h3 { margin: 0 0 0.4em; font-size: 1em; }
.deploy-card p { font-size: 0.88em; color: var(--muted); }
.deploy-card .outcome { font-size: 0.8em; color: var(--accent); margin-top: 0.5em; font-weight: 600; }

/* Footer */
footer {
  border-top: 1px solid var(--border); padding: 2em 0;
  text-align: center; color: var(--muted); font-size: 0.85em;
}

footer a { color: var(--muted); }
footer a:hover { color: var(--fg); }

/* Page hero (non-home pages) */
.page-hero {
  padding: 3em 0 1.5em;
  text-align: center;
}

.page-hero h1 {
  font-size: 2em; font-weight: 800; letter-spacing: -0.03em; margin-bottom: 0.3em;
}

.page-hero .subtitle {
  color: var(--muted); font-size: 1.1em; max-width: 540px; margin: 0 auto;
}

/* Pricing tiers */
.tier-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.25em; margin: 2em 0; }
@media (max-width: 700px) { .tier-grid { grid-template-columns: 1fr; } }

.tier {
  background: var(--card-bg); border: 1px solid var(--border);
  border-radius: 10px; padding: 2em 1.5em; text-align: center;
  position: relative;
}

.tier.featured {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}

.tier .badge {
  position: absolute; top: -0.7em; left: 50%; transform: translateX(-50%);
  background: var(--accent); color: #fff; font-size: 0.7em; font-weight: 700;
  padding: 0.2em 0.8em; border-radius: 99px; text-transform: uppercase; letter-spacing: 0.05em;
}

.tier h3 { font-size: 1.15em; font-weight: 700; margin-bottom: 0.3em; }
.tier .price { font-size: 2em; font-weight: 800; color: var(--accent); margin: 0.3em 0; }
.tier .price span { font-size: 0.4em; font-weight: 400; color: var(--muted); }
.tier .desc { font-size: 0.88em; color: var(--muted); margin-bottom: 1em; }
.tier ul { text-align: left; margin-bottom: 1.5em; }
.tier ul li { font-size: 0.88em; }

/* Feature list with checks */
.feature-list { list-style: none; padding: 0; }
.feature-list li { padding: 0.4em 0 0.4em 1.6em; position: relative; font-size: 0.9em; }
.feature-list li::before { content: "✓"; color: var(--green); position: absolute; left: 0; font-weight: 700; }

/* Responsive */
@media (max-width: 600px) {
  .page-hero h1 { font-size: 1.6em; }
  .container { padding: 0 1em; }

  /* Mobile header: stack logo above nav */
  header { padding: 1em 0; }

  header .container {
    flex-direction: column;
    align-items: center;
    gap: 0.6em;
  }

  header .logo {
    font-size: 1.05em;
    letter-spacing: 0.01em;
    text-align: center;
    display: block;
    width: 100%;
    padding-bottom: 0.4em;
    border-bottom: 1px solid var(--border);
  }

  header nav {
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5em 1em;
    width: 100%;
  }

  header nav a { font-size: 0.85em; }

  /* Hero receipt: prevent overflow */
  .hero-receipt pre { font-size: 0.7em; }
  .hero h1 { font-size: 1.6em; }
  .hero { padding: 2.5em 0 1.5em; }
}