/* ---------- Design system for ModelThinker web stories ------------------- */
/* Inspired by Parable of the Polygons (Vi Hart & Nicky Case, 2014). */

:root {
  --primary:      #4C6EF5;
  --primary-dim:  #7C93F8;
  --accent:       #F76707;
  --success:      #37B24D;
  --warn:         #F59F00;
  --danger:       #E03131;
  --ink:          #1A1D29;
  --text:         #2C3140;
  --muted:        #6C7382;
  --line:         #E4E7EE;
  --bg:           #FBFCFF;
  --bg-elev:      #FFFFFF;
  --bg-soft:      #F5F7FC;

  --font-sans:   "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-serif:  "Source Serif Pro", Georgia, "Times New Roman", serif;

  --radius-sm: 8px;
  --radius:    14px;
  --radius-lg: 22px;
  --shadow:    0 6px 24px rgba(28, 34, 56, 0.08);
  --shadow-lg: 0 18px 60px rgba(28, 34, 56, 0.14);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* ---------- Layout ------------------------------------------------------- */

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 32px 24px 96px;
}

.wide {
  max-width: 960px;
  margin: 0 auto;
  padding: 32px 24px;
}

/* ---------- Typography --------------------------------------------------- */

h1, h2, h3, h4 {
  font-family: var(--font-sans);
  color: var(--ink);
  line-height: 1.2;
  letter-spacing: -0.01em;
}

h1 { font-size: 44px; margin: 8px 0 12px; font-weight: 800; }
h2 { font-size: 30px; margin: 56px 0 12px; font-weight: 700; }
h3 { font-size: 20px; margin: 32px 0 8px; font-weight: 700; }

.subtitle {
  font-size: 20px;
  color: var(--muted);
  margin: 0 0 32px;
  line-height: 1.4;
}

.byline {
  font-size: 14px;
  color: var(--muted);
  margin: 0 0 8px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

p { margin: 0 0 16px; }

.callout {
  background: var(--bg-soft);
  border-left: 4px solid var(--primary);
  padding: 16px 20px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 24px 0;
}

.callout.warn {
  border-left-color: var(--warn);
  background: #FFF9EC;
}

.callout.aha {
  border-left-color: var(--accent);
  background: #FFF5EF;
}

blockquote {
  margin: 24px 0;
  padding: 8px 24px;
  border-left: 4px solid var(--line);
  color: var(--muted);
  font-style: italic;
}

/* ---------- Sim card ----------------------------------------------------- */

.sim {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin: 32px 0;
  box-shadow: var(--shadow);
}

.sim-title {
  font-size: 14px;
  font-weight: 700;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 0 0 12px;
}

.sim-canvas {
  display: block;
  width: 100%;
  border-radius: var(--radius);
  background: var(--bg-soft);
  cursor: pointer;
  touch-action: none;
}

.sim-controls {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  align-items: center;
  margin-top: 16px;
}

.sim-metrics {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.metric {
  background: var(--bg-soft);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
}
.metric .label { font-size: 12px; color: var(--muted); text-transform: uppercase; letter-spacing: 0.05em; }
.metric .value { font-size: 22px; font-weight: 700; color: var(--ink); font-variant-numeric: tabular-nums; }
.metric .delta { font-size: 12px; color: var(--muted); }

/* ---------- Buttons ------------------------------------------------------ */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border-radius: 999px;
  border: 1.5px solid var(--line);
  background: var(--bg-elev);
  color: var(--text);
  font-family: inherit;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.08s ease, box-shadow 0.2s ease, background 0.2s ease;
  user-select: none;
}
.btn:hover { transform: translateY(-1px); box-shadow: var(--shadow); }
.btn:active { transform: translateY(0); }

.btn-primary {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}
.btn-primary:hover { background: #3B5BDB; border-color: #3B5BDB; }

.btn-accent {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}
.btn-accent:hover { background: #DC5A00; border-color: #DC5A00; }

.btn-ghost {
  background: transparent;
  border-color: transparent;
  color: var(--primary);
}
.btn-ghost:hover { background: var(--bg-soft); }

.btn:disabled { opacity: 0.5; cursor: not-allowed; transform: none; box-shadow: none; }

/* ---------- Sliders ------------------------------------------------------ */

.slider-block {
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-width: 180px;
  flex: 1;
}
.slider-label {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  color: var(--muted);
  font-weight: 600;
}
.slider-label .value { color: var(--ink); font-variant-numeric: tabular-nums; }
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--line);
  outline: none;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--primary);
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(76, 110, 245, 0.4);
  border: 3px solid white;
}
input[type="range"]::-moz-range-thumb {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--primary);
  cursor: pointer;
  border: 3px solid white;
}

/* ---------- Progress bar (meter) ---------------------------------------- */

.meter {
  background: var(--line);
  border-radius: 999px;
  height: 14px;
  overflow: hidden;
  position: relative;
}
.meter-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  transition: width 0.4s ease;
  border-radius: 999px;
}

/* ---------- Landing cards ----------------------------------------------- */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin: 32px 0;
}
.card {
  display: block;
  padding: 24px;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  color: inherit;
  text-decoration: none;
  transition: transform 0.12s ease, box-shadow 0.2s ease;
  box-shadow: var(--shadow);
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }
.card.planned { opacity: 0.55; }
.card .badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 6px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  background: var(--bg-soft);
  color: var(--muted);
  margin-bottom: 8px;
}
.card .badge.live { background: #E7F5EA; color: var(--success); }
.card h3 { margin: 0 0 6px; }
.card p { margin: 0; color: var(--muted); font-size: 14px; }

/* ---------- Top nav (back to main) --------------------------------------- */

.top-nav {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: -8px 0 24px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
  font-weight: 600;
}
.top-nav a {
  color: var(--primary);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 10px;
  border-radius: 8px;
  transition: background 0.15s ease;
}
.top-nav a:hover { background: var(--bg-soft); }
.top-nav .spacer { flex: 1; }
.top-nav .crumb { color: var(--muted); font-weight: 500; }
.top-nav .lang-switch {
  background: var(--bg-soft);
  color: var(--ink);
  border: 1px solid var(--line);
  font-size: 12px;
  font-weight: 700;
  padding: 4px 10px;
  letter-spacing: 0.03em;
}
.top-nav .lang-switch:hover {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

/* ---------- Footer nav --------------------------------------------------- */

.next-nav {
  margin: 64px 0 0;
  padding: 32px 0;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}
.next-nav a { color: var(--primary); text-decoration: none; font-weight: 600; }
.next-nav a:hover { text-decoration: underline; }

/* ---------- Utility ------------------------------------------------------ */

.hidden { display: none !important; }
.center { text-align: center; }
.mono { font-family: "SF Mono", Menlo, Consolas, monospace; font-size: 90%; }

@media (max-width: 640px) {
  h1 { font-size: 32px; }
  h2 { font-size: 24px; margin-top: 40px; }
  .wrap { padding: 20px 16px 64px; }
  .sim { padding: 16px; margin: 24px 0; }
}