Gallery Widget decrease Font size and color

Hello, I am using the Gallery Widget on my sidebar. It looks great. However, when you click an image it displays it with the file name above it. I am ok with this but it is too large, too close to the image and I would like it to be grey.

Is there an additional CSS to add that would do this?

(ideally, I wish this theme allowed me to add a caption that only showed when the image is clicked. I see that it allows for caption input that shows up in the gallery featured image grid but that is too cluttered looking and not enough space)

Lastly, there is a lot of whitespace and padding at the bottom of the page above the footer. How do I decrease this?

Thank you!

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