:root {
  --bg: #020617;
  --bg-panel: #071126;
  --bg-board: #050b1c;
  --grid: #0d1a36;
  --ink: #c9d8f5;
  --muted: #6d82ab;
  --accent: #3b82f6;
  --accent-soft: #1d4ed8;
  --glow: rgba(37, 99, 235, 0.35);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html,
body {
  min-height: 100%;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background:
    radial-gradient(circle at top, #0b1d44 0%, transparent 42%),
    linear-gradient(180deg, #01030d 0%, var(--bg) 100%);
  color: var(--ink);
}

.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.25rem;
  padding: 1.5rem;
}

.header h1 {
  letter-spacing: 0.45em;
  text-transform: uppercase;
  font-weight: 700;
  font-size: 1.6rem;
  color: #8eb4ff;
  text-shadow: 0 0 18px var(--glow);
}

.layout {
  display: flex;
  align-items: stretch;
  gap: 1.25rem;
}

.panel {
  width: 160px;
  background: var(--bg-panel);
  border: 1px solid #122044;
  border-radius: 12px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  box-shadow: 0 0 28px rgba(2, 8, 24, 0.8);
}

.stat,
.next {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.label {
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

.value {
  font-size: 1.6rem;
  font-variant-numeric: tabular-nums;
  color: #dbe7ff;
}

.help h2 {
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.5rem;
}

.help p {
  font-size: 0.85rem;
  color: #9eb3d8;
  margin-bottom: 0.3rem;
}

kbd {
  display: inline-block;
  min-width: 1.4rem;
  padding: 0.05rem 0.35rem;
  border: 1px solid #1e3a6a;
  border-bottom-width: 2px;
  border-radius: 4px;
  background: #0a1833;
  font-size: 0.75rem;
  color: #b8ccf0;
}

.board-wrap {
  position: relative;
  background: var(--bg-board);
  border: 2px solid #163064;
  border-radius: 8px;
  box-shadow:
    0 0 0 1px #07101f,
    0 0 40px var(--glow);
  overflow: hidden;
}

#board {
  display: block;
  background: #030814;
}

.next canvas {
  display: block;
  margin-top: 0.4rem;
  background: #030814;
  border: 1px solid #122044;
  border-radius: 8px;
}

#start-btn {
  margin-top: auto;
  border: 2px solid var(--muted);
  border-radius: 8px;
  padding: 0.7rem 0.85rem;
  background: transparent;
  color: var(--muted);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  cursor: pointer;
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}

#start-btn:hover {
  background: var(--muted);
  color: var(--bg);
  border-color: var(--bg);
}

.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background: rgba(2, 7, 20, 0.78);
  text-align: center;
}

.overlay.hidden {
  display: none;
}

#overlay-title {
  font-size: 1.8rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: #9ec2ff;
}

#overlay-sub {
  color: var(--muted);
  font-size: 0.95rem;
}

@media (max-width: 760px) {
  .layout {
    flex-direction: column;
    align-items: center;
  }

  .panel {
    width: 300px;
    flex-direction: row;
    flex-wrap: wrap;
  }

  .help {
    width: 100%;
  }
}