In documentation some icons are hard to make out when not in dark mode

[WillAdams]

While the image:

https://raw.githubusercontent.com/derkork/openscad-graph-editor/master/Icons/add0000.png

is perfectly readable in its original state, or when viewed in the default dark mode:

it is effectively invisible when not in dark mode:

[derkork]

I see (that I don't see). Looks like I have to make a separate copy of the icons for the docs which isn't transparent. Thanks for the heads-up!