I wanted to use SVG elements to highlight sections of a map without having to reproduce the text and other parts of it, so I wanted it to darken only.
First I needed to set titles on the elements so that I could identify them. Couldn’t figure out good keyboard shortcuts in Inkscape, so I used Autohotkey to click on the title box in the Object Properties docker and then move the mouse back to the original position.
Support for mix-blend-mode on SVG elements is limited. I worked around that by using the image as the background on a div with fixed width, removing height and width on the SVG to make it responsive, and applying mix-blend-mode on my whole SVG.
Also, the platform I was doing this on didn’t like SVGs, so I base64-encoded the data, then fetched and decoded it. Hack upon hack upon hack, but it seems to be working.