/* 全局与背景 */
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: #000 url('images/星空背景2.png') center / cover fixed no-repeat;
  overflow: hidden;
  color: #fff;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}


/* 画布覆盖全屏 */
#starCanvas {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  display: block;
}

/* 浮层UI */
.ui {
  position: fixed;
  top: 24px;
  left: 24px;
  backdrop-filter: blur(6px);
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 14px;
  padding: 16px 18px;
  box-shadow: 0 8px 28px rgba(0,0,0,0.35);
}

.title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 10px;
  letter-spacing: 0.5px;
}

.controls { display: flex; gap: 12px; }

.btn {
  appearance: none;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 10px 16px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  color: #fff;
  background: linear-gradient(135deg, #71BB39, #5a9c2a);
  box-shadow: 0 6px 18px rgba(113, 187, 57, 0.35);
  transition: transform .12s ease, filter .12s ease, opacity .2s ease;
}

.btn:hover { transform: translateY(-1px); filter: brightness(1.05); }
.btn:active { transform: translateY(0); filter: brightness(0.98); }
.btn[disabled] { opacity: 0.55; cursor: not-allowed; box-shadow: none; }

/* 响应式适配 */
@media (max-width: 480px) {
  .ui { left: 12px; right: 12px; top: 12px; padding: 12px; }
  .controls { gap: 8px; }
  .btn { flex: 1; padding: 10px 12px; font-size: 13px; }
}