* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at top, #1d3557 0%, #0b1320 45%, #05070d 100%);
  color: #eef2ff;
}

button,
input {
  font: inherit;
}

.app {
  width: min(1080px, calc(100% - 32px));
  margin: 0 auto;
  padding: 32px 0;
  display: grid;
  grid-template-columns: minmax(280px, 360px) minmax(280px, 1fr);
  gap: 24px;
  align-items: start;
}

.panel,
.board-wrap {
  background: rgba(10, 15, 28, 0.78);
  border: 1px solid rgba(166, 180, 255, 0.18);
  border-radius: 24px;
  box-shadow: 0 18px 50px rgba(0, 0, 0, 0.28);
  backdrop-filter: blur(10px);
}

.panel {
  padding: 28px;
}

.eyebrow {
  margin: 0 0 8px;
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: #91a7ff;
}

h1 {
  margin: 0;
  font-size: clamp(32px, 4vw, 44px);
}

.subtitle {
  margin: 14px 0 0;
  line-height: 1.6;
  color: #c7d2fe;
}

.stats {
  margin-top: 24px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.stat-card {
  padding: 16px;
  border-radius: 16px;
  background: rgba(30, 41, 59, 0.9);
  border: 1px solid rgba(148, 163, 184, 0.2);
}

.stat-card span {
  display: block;
  font-size: 14px;
  color: #a5b4fc;
}

.stat-card strong {
  display: block;
  margin-top: 8px;
  font-size: 30px;
}

.actions {
  margin-top: 24px;
  display: grid;
  gap: 16px;
}

#start-button {
  border: 0;
  border-radius: 999px;
  padding: 14px 18px;
  font-weight: 700;
  color: #08111f;
  background: linear-gradient(135deg, #7dd3fc, #86efac);
  cursor: pointer;
}

#start-button:hover {
  filter: brightness(1.04);
}

.speed-control {
  display: grid;
  gap: 8px;
  color: #cbd5e1;
}

#speed {
  width: 100%;
}

.status {
  min-height: 24px;
  margin: 18px 0 0;
  color: #fcd34d;
}

.board-wrap {
  padding: 22px;
  display: grid;
  justify-items: center;
  gap: 22px;
}

#board {
  width: min(100%, 560px);
  aspect-ratio: 1;
  border-radius: 20px;
  background: #0b1220;
  border: 1px solid rgba(148, 163, 184, 0.2);
}

.controls {
  display: grid;
  gap: 10px;
  justify-items: center;
}

.control-row {
  display: flex;
  gap: 10px;
}

.controls button {
  width: 56px;
  height: 56px;
  border: 1px solid rgba(148, 163, 184, 0.22);
  border-radius: 16px;
  background: rgba(30, 41, 59, 0.92);
  color: #eef2ff;
  cursor: pointer;
}

.controls button:active {
  transform: translateY(1px);
}

@media (max-width: 860px) {
  .app {
    grid-template-columns: 1fr;
    padding: 16px 0 24px;
  }

  .panel,
  .board-wrap {
    border-radius: 20px;
  }

  .panel {
    padding: 22px;
  }
}