Change titles on images

Hello,

I just finished my page with this theme and I like the result but one detail doesn’t convince me.

On the pictures in the home page, as you can see here, https://www.handmadepoetryeditorial.com, titles are white and they are difficult to see. Is it possible to do, as on the pictures when you go to the post, a semi-trasparent box under this titles and black/other colours letters?

Thanks so much!

M