html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  overflow: hidden;
  background: black;
}

canvas {
  display: block; /* Removes gap below canvas */
}

/* Wrapper controls position for BOTH toggle + sliders */
#gui-wrapper {
  position: fixed;
  bottom: 100px;   /* move the block up/down */
  left: 10px;      /* move the block left/right */
  display: flex;
  flex-direction: column; /* arrow on top, sliders below */
  align-items: flex-start;
  gap: 8px;
  z-index: 100;
}

/* Arrow button */
#gui-toggle {
  width: 32px;
  height: 32px;
  background: rgba(0, 0, 0, 0.6);
  color: #fff;
  font-size: 18px;
  text-align: center;
  line-height: 32px;
  border-radius: 4px;
  cursor: pointer;
  user-select: none;
}

/* Slider panel */
#gui-container {
  background: rgba(0, 0, 0, 0.4);
  padding: 6px;
  border-radius: 6px;
  z-index: 99;
}

#gui-container.hidden {
  display: none;
}