Making the icons:
* icons are in https://www.figma.com/file/2JsWwIZWlWEPJ1YwwLkusj/Sumatra-icon-(Copy)?node-id=0%3A1
* colors for background of the icon are https://material.io/design/color/the-color-system.html#tools-for-picking-colors
  using A200 => A400 transition
* export to .png using 512h
* convert to .ico with https://www.icoconverter.com/

Online icon editor: https://redketchup.io/icon-editor could be used to improve the low-resolution icons.
