.canvas_mask {
    position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 99%;
      background: 
          linear-gradient(to right, 
              transparent 88%, 
              rgba(22, 27, 31, 0.5) 93%, 
              rgba(22, 27, 31, 1) 100%), 
              linear-gradient(to left, 
              transparent 88%, 
              rgba(22, 27, 31, 0.5) 93%, 
              rgba(22, 27, 31, 1) 100%), 
         
          linear-gradient(to top, 
              transparent 78%, 
              rgba(22, 27, 31, 0.7) 85%, 
              rgba(22, 27, 31, 1) 90%); 
      pointer-events: none;
  }