Salient theme Help



For the page portfolio, I use the option " Meta below thumb w / links one hover ". This option shows a bottom of color on the thumb ( work-info-bg ) as well as a link towards single page. I wish to invert the effect in the hover.
I would want that by défault the thumb is masked by the color and in the hover the background on the thumb disappears.
How may I realize this adaptation?
Thank you for your help(assistant).