:root {
  --bg: #0f1722;
  --panel: #16212f;
  --panel-2: #1d2b3c;
  --text: #e8eef5;
  --muted: #8aa0b5;
  --ga: #4ade80;
  --footer-h: 74px;
}

* { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, Roboto, Arial, sans-serif;
  background: radial-gradient(1100px 600px at 50% -10%, #1b2a3d 0%, var(--bg) 60%);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  padding-bottom: var(--footer-h);
}

header {
  text-align: center;
  padding: 16px 12px 4px;
  flex: 0 0 auto;
}

header h1 {
  margin: 0;
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: 0.3px;
}

header p {
  margin: 6px 0 0;
  font-size: 0.86rem;
  color: var(--muted);
}

/* ---- main two-column layout ---- */
.arena {
  flex: 1 1 auto;
  display: flex;
  gap: 22px;
  justify-content: center;
  align-items: stretch;
  padding: 14px 22px;
  max-width: 1100px;
  width: 100%;
  margin: 0 auto;
}

.game-col {
  display: flex;
  align-items: center;
  justify-content: center;
}

.canvas-wrap {
  border-radius: 14px;
  overflow: hidden;
  line-height: 0;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.45);
  border: 2px solid rgba(255, 255, 255, 0.08);
}

canvas#gameCanvas {
  display: block;
  height: min(720px, calc(100vh - var(--footer-h) - 130px));
  width: auto;
  image-rendering: pixelated;
  image-rendering: crisp-edges;
}

/* ---- sidebar ---- */
.side-col {
  width: 360px;
  max-width: 42vw;
  display: flex;
  flex-direction: column;
  gap: 14px;
  align-self: center;
}

.stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}

.stat {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid rgba(255, 255, 255, 0.07);
  border-radius: 12px;
  padding: 12px 14px;
}

.stat .k {
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.7px;
  color: var(--muted);
}

.stat .v {
  font-size: 1.7rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: var(--ga);
  margin-top: 2px;
}

.card {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid rgba(255, 255, 255, 0.07);
  border-radius: 12px;
  padding: 12px 14px;
}

.card-label {
  font-size: 0.66rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.7px;
  margin-bottom: 8px;
}

canvas.curve {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 8px;
  background: rgba(0, 0, 0, 0.28);
}

.legend ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.legend li {
  font-size: 0.82rem;
  line-height: 1.35;
  color: #cdd9e6;
  display: flex;
  gap: 9px;
  align-items: flex-start;
}

.legend b { color: var(--text); }

.sw {
  flex: 0 0 auto;
  width: 13px;
  height: 13px;
  border-radius: 4px;
  margin-top: 2px;
}
.sw.flock { background: #ffd24a; }
.sw.sensor { background: #13284a; border: 2px solid #fff; }
.sw.evolve { background: var(--ga); }

/* ---- footer controls ---- */
.controls {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: var(--footer-h);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  flex-wrap: wrap;
  padding: 0 14px;
  background: rgba(12, 18, 26, 0.9);
  backdrop-filter: blur(8px);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  z-index: 10;
}

.controls label { font-size: 0.85rem; color: var(--muted); }
.controls .speed { display: flex; align-items: center; gap: 10px; }
.controls .speed strong { color: var(--text); min-width: 46px; display: inline-block; }
.controls input[type="range"] { width: 240px; accent-color: var(--ga); }

.controls button {
  background: var(--panel-2);
  color: var(--text);
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 9px;
  padding: 9px 18px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background 0.15s, transform 0.05s;
}

.controls button:hover { background: #26384d; }
.controls button:active { transform: translateY(1px); }

/* ---- responsive: stack on narrow screens ---- */
@media (max-width: 820px) {
  .arena { flex-direction: column; align-items: center; }
  .side-col { width: 100%; max-width: 420px; }
  canvas#gameCanvas { height: min(520px, 64vh); }
}