html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #000;
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  user-select: none;
}

#ui-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 10;
}

.panel {
  position: absolute;
  pointer-events: auto;
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 14px;
  padding: 12px 14px;
  color: #fff;
  box-shadow: 0 6px 24px rgba(0,0,0,0.25);
}

.top-left {
  top: 18px;
  left: 18px;
}

.top-right {
  top: 18px;
  right: 18px;
}

.center {
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 10px;
  align-items: center;
}

.label {
  font-size: 12px;
  opacity: 0.8;
  margin-bottom: 6px;
  letter-spacing: 1px;
}

.btn-group {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  justify-content: center;
}

button {
  background: rgba(255, 255, 255, 0.12);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #fff;
  padding: 8px 14px;
  border-radius: 10px;
  cursor: pointer;
  font-size: 13px;
  transition: all 0.2s ease;
}

button:hover {
  background: rgba(255, 255, 255, 0.22);
  transform: translateY(-1px);
}

button.active {
  background: rgba(255, 255, 255, 0.85);
  color: #1a1a1a;
  border-color: rgba(255, 255, 255, 0.9);
}

button.primary {
  background: rgba(255, 255, 255, 0.9);
  color: #1a1a1a;
  font-weight: 600;
  padding: 10px 20px;
  font-size: 14px;
}

button.primary:hover {
  background: #fff;
}

.hint {
  font-size: 12px;
  opacity: 0.7;
  margin: 4px 0 0;
}

.hidden {
  opacity: 0;
  pointer-events: none;
}