html, body {
  margin: 0;
  height: 100%;
  background: #000;
  color: #e8e8f0;
  overflow: hidden;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-tap-highlight-color: transparent;
  touch-action: none;
}
canvas { display: block; }

.back {
  position: fixed;
  top: 14px;
  left: 14px;
  z-index: 20;
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: rgba(255, 255, 255, .08);
  border: 1px solid rgba(255, 255, 255, .14);
  color: #fff;
  text-decoration: none;
  font-size: 20px;
  backdrop-filter: blur(6px);
}

.hint {
  position: fixed;
  left: 0;
  right: 0;
  bottom: max(18px, env(safe-area-inset-bottom));
  z-index: 20;
  text-align: center;
  font-size: 13px;
  letter-spacing: .02em;
  color: rgba(255, 255, 255, .55);
  pointer-events: none;
}

.ui {
  position: fixed;
  left: 50%;
  bottom: max(44px, calc(env(safe-area-inset-bottom) + 30px));
  transform: translateX(-50%);
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 12px;
}
.ui button {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, .2);
  background: rgba(255, 255, 255, .07);
  color: #fff;
  font-size: 18px;
  cursor: pointer;
  backdrop-filter: blur(6px);
}
.ui button:active { background: rgba(255, 255, 255, .2); }
.ui .label {
  min-width: 130px;
  text-align: center;
  font-size: 14px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, .85);
}