:root{
  --bg: #0b1020;
  --panel: #141a2e;
  --text: #e9ecf2;
  --muted: #9aa3b2;
  --accent: #7dd3fc;
  --accent-2: #34d399;
  --danger: #fb7185;
  --grid: #1d2542;
  --snake: #8b5cf6;
  --snake-head: #a78bfa;
  --food: #fbbf24;
  --shadow: 0 8px 28px rgba(0,0,0,.35);
}

* { box-sizing: border-box; }

html, body {
  min-height: 100%;
  height: 100%;
  margin: 0;
  background: radial-gradient(1200px 800px at 30% -10%, #11183a 0%, var(--bg) 40%, #060912 100%);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "PingFang SC", "Noto Sans CJK", "Microsoft YaHei", Arial, sans-serif;
}

.app{
  max-width: 920px;
  margin: 0 auto;
  padding: 24px;
}

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

h1{
  margin: 0;
  font-size: 28px;
  letter-spacing: .5px;
}

.controls{
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

button{
  background: linear-gradient(180deg, #1f2645, #121833);
  color: var(--text);
  border: 1px solid #2b3566;
  padding: 10px 14px;
  border-radius: 12px;
  cursor: pointer;
  box-shadow: var(--shadow);
  transition: transform .06s ease, background .2s ease, border-color .2s ease, opacity .2s ease;
  font-weight: 600;
}
button:hover{ transform: translateY(-1px); border-color: #4250a8; }
button:active{ transform: translateY(0); opacity: .9; }
button.primary{
  background: linear-gradient(180deg, #2563eb, #1d4ed8);
  border-color: #3b82f6;
}

.speed{
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--muted);
  padding-left: 8px;
  border-left: 1px solid #2b3566;
  margin-left: 4px;
}
#speed-range{ accent-color: var(--accent); }
#speed-label{
  min-width: 24px;
  text-align: right;
  color: var(--accent);
  font-weight: 700;
}

.stats{
  display: flex;
  gap: 16px;
  margin: 14px 0 10px;
  color: var(--muted);
  flex-wrap: wrap;
}
.stats span{ color: var(--accent-2); font-weight: 700; }
.hint{ opacity: .85; }

.board-wrap{
  position: relative;
  width: 100%;
  max-width: 480px;
  aspect-ratio: 1 / 1;
  margin: 16px auto 8px;
  border-radius: 20px;
  background: linear-gradient(180deg, #101735, #0d142c);
  padding: 14px;
  box-shadow: var(--shadow);
}

#board{
  display: block;
  width: 100%;
  height: 100%;
  background: repeating-linear-gradient(
    90deg, var(--grid) 0 1px, transparent 1px 24px
  ), repeating-linear-gradient(
    0deg, var(--grid) 0 1px, transparent 1px 24px
  ), #0b1130;
  border-radius: 12px;
}

/* 结束遮罩 */
.overlay{
  position: absolute;
  inset: 14px;
  background: rgba(6, 10, 25, .75);
  display: grid;
  place-items: center;
  border-radius: 12px;
  backdrop-filter: blur(2px);
}
.overlay.hidden{ display: none; }
.overlay-card{
  background: linear-gradient(180deg, #192146, #0f1533);
  border: 1px solid #2b3566;
  border-radius: 16px;
  padding: 20px 18px;
  text-align: center;
  width: min(90%, 320px);
  box-shadow: var(--shadow);
}
.overlay-card h2{ margin: 0 0 8px; font-size: 22px; }
.overlay-card p{ margin: 0 0 14px; color: var(--muted); }

.footer{
  margin-top: 10px;
  color: var(--muted);
  text-align: center;
  font-size: 13px;
}

/* 小屏优化 */
@media (max-width: 520px){
  .topbar{ flex-direction: column; align-items: flex-start; }
  .controls{ width: 100%; }
  .board-wrap{ padding: 10px; }
  .overlay{ inset: 10px; }
}