Screenshot 2024-01-12 at 01.32.35.png
but it already works no?
you can use the settings for this, instead of css:
in customize → project thumbnails → project thumbnail mouseover
Screenshot 2024-01-12 at 01.34.09.png
use white bg color and opacity like 0 i think or 100
and in:
customize → project thumbnails → project title
Screenshot 2024-01-12 at 01.34.22.png
show title on mouseover
or maybe i don't understand what you're trying to do correctly