* {
  box-sizing: border-box;
}

:root {
  --panel-bg: rgba(255, 255, 255, 0.72);
  --panel-border: rgba(148, 163, 184, 0.35);
  --ink: #0f172a;
  --muted: #475569;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at 8% 10%, rgba(125, 211, 252, 0.55) 0, transparent 35%),
    radial-gradient(circle at 92% 85%, rgba(134, 239, 172, 0.4) 0, transparent 30%),
    linear-gradient(170deg, #f8fafc, #e2e8f0);
  color: var(--ink);
}

.container {
  width: min(96vw, 940px);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 10px;
}

h1 {
  margin: 0;
  font-size: clamp(24px, 3vw, 36px);
  letter-spacing: 0.02em;
}

.mode {
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: #075985;
  background: rgba(186, 230, 253, 0.75);
  border: 1px solid rgba(14, 116, 144, 0.24);
}

.hint {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 14px;
}

.game-card {
  padding: 10px;
  border-radius: 18px;
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  box-shadow: 0 14px 45px rgba(15, 23, 42, 0.16);
  backdrop-filter: blur(6px);
}

canvas {
  width: 100%;
  height: auto;
  border-radius: 12px;
  background: #ffffff;
  border: 2px solid #0f172a;
  display: block;
  touch-action: manipulation;
}

@media (max-width: 640px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
    gap: 8px;
  }
}