Settings on my site

Hello.
Can you please advise me on the CSS settings on my site? I have a modern scheme set up where the titles of the articles are in the pictures. When I set the CSS, a black background is inserted after the text set in the image (see on screen: https://mixxermusic.com/wp-content/uploads/2020/05/Snímek-obrazovky-2020-05-11-v-16.00.15.png) Is there any way to set it up correctly?

Alternatively, how to set the social buttons to be in a transparent background. Thank you for help.

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