.glass {
  width: 175px;
  height: 175px;
  position: absolute;
  border-radius: 50%;
  cursor: crosshair;
  
  /* Multiple box shadows to achieve the glass effect */
  box-shadow:
    0 0 0 7px rgba(255, 255, 255, 0.85),
    0 0 7px 7px rgba(0, 0, 0, 0.25), 
    inset 0 0 40px 2px rgba(0, 0, 0, 0.25);
  
  /* hide the glass by default */
  display: none;
}