Remove grey overlay of blog excerpts / Masonry Grid – posts are same size

Hi.
I am applying the Bento theme to my website and I am having a couple of problems.

1. I am trying to remove the grey overlay of blog excerpts/pictures with no success, so far. How can I have no overlay on them, just show the title on the hover?

2. I have used Masonry Grid to my blog page – but the cells of posts stayed same size and with the same sized margins (I want no margins between them and different sizes of pictures – the same as it was in your demo)

Thank you for your help.

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