html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: #06050e; /* Cosmic deep dark violet */
  color: #ffffff;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  user-select: none;
  -webkit-user-select: none;
  touch-action: none; /* Prevents browser zooming, scrolling, or panning during touch interaction */
}

#game-container {
  position: relative;
  width: 100vw;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
}

canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: block;
  z-index: 1;
}

canvas:focus {
  outline: none;
}

/* Accessible screen-reader HUD */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

#ui-layer {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 10;
}

.screen {
  pointer-events: auto;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.btn {
  padding: 16px 32px;
  font-size: 20px;
  font-weight: bold;
  color: #fff;
  background-color: #06b6d4;
  border: 2px solid #ffffff;
  border-radius: 8px;
  cursor: pointer;
  box-shadow: 0 4px 6px rgba(0,0,0,0.3);
  transition: transform 0.1s, background-color 0.2s;
  margin-top: 140px;
}

.btn:hover {
  background-color: #0891b2;
  transform: scale(1.05);
}

.btn:active {
  transform: scale(0.95);
}