html,
body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  background: #0d0f0f;
}

/* 照準はOSのカーソルとして出し、描画の遅れなしに追従させる */
#screen {
  display: block;
  width: 100vw;
  height: 100vh;
  cursor: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='32' height='32'><g fill='none' stroke-linecap='round'><path d='M16 4v7M16 21v7M4 16h7M21 16h7' stroke='black' stroke-opacity='0.7' stroke-width='3'/><path d='M16 4v7M16 21v7M4 16h7M21 16h7' stroke='%23f4ead2' stroke-width='1.3'/></g><circle cx='16' cy='16' r='1.6' fill='%23f4ead2' stroke='black' stroke-width='0.8'/></svg>") 16 16, crosshair;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
}