* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  width: 100%;
  height: 100%;
  background: #05070a;
  overflow: hidden;
  touch-action: none;
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
}

#glcanvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  cursor: none;
}

.controls {
  position: fixed;
  top: 20px;
  left: 20px;
  display: flex;
  gap: 10px;
  z-index: 10;
}

.toggle-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.18);
  background: rgba(20, 24, 32, 0.45);
  backdrop-filter: blur(6px);
  color: rgba(235, 240, 245, 0.95);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  padding: 0;
  transition: opacity 0.25s ease, background 0.25s ease, border-color 0.25s ease, transform 0.15s ease;
}

.toggle-btn svg {
  width: 20px;
  height: 20px;
}

.toggle-btn:hover {
  border-color: rgba(255, 255, 255, 0.35);
  transform: scale(1.06);
}

.toggle-btn[aria-pressed="false"] {
  opacity: 0.35;
  background: rgba(20, 24, 32, 0.25);
}

.hint {
  position: fixed;
  left: 50%;
  bottom: 8vh;
  transform: translateX(-50%);
  color: rgba(235, 240, 245, 0.75);
  font-size: 13px;
  letter-spacing: 0.18em;
  text-shadow: 0 1px 6px rgba(0, 0, 0, 0.6);
  pointer-events: none;
  transition: opacity 1.2s ease;
  opacity: 1;
}

.hint.faded {
  opacity: 0;
}

.fallback {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: #dfe6ee;
  background: #05070a;
  line-height: 1.8;
  font-size: 14px;
  padding: 2rem;
}

.hidden {
  display: none;
}