html, body {
  margin: 0;
  height: 100%;
  background: #000;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  overscroll-behavior: none;
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
}

canvas {
  background: #000;
  box-shadow: 0 0 60px rgba(180, 100, 255, 0.2);
  touch-action: none;
}

.ctrl-btn {
  position: fixed;
  bottom: max(18px, env(safe-area-inset-bottom));
  z-index: 10;
  width: 84px;
  height: 84px;
  border-radius: 50%;
  font-size: 30px;
  line-height: 1;
  color: rgba(255, 94, 196, 0.85);
  background: rgba(10, 12, 30, 0.45);
  border: 1px solid rgba(255, 94, 196, 0.4);
  touch-action: none;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

.ctrl-btn:active {
  background: rgba(255, 94, 196, 0.25);
  border-color: #ff5ec4;
}

.ctrl-left { left: 18px; }
.ctrl-right { right: 18px; }

#fsBtn {
  position: fixed;
  top: 14px;
  right: 14px;
  z-index: 10;
  font-family: monospace;
  font-size: 12px;
  letter-spacing: 1px;
  color: #ff5ec4;
  background: rgba(10, 12, 30, 0.6);
  border: 1px solid rgba(255, 94, 196, 0.5);
  border-radius: 4px;
  padding: 6px 10px;
  cursor: pointer;
}

#fsBtn:hover {
  background: rgba(255, 94, 196, 0.15);
  border-color: #ff5ec4;
}