Theme adjustment question

Hello!

http://staging-sofianosorthopedikagr.kinsta.cloud/%CE%BA%CE%B1%CF%84-%CE%BF%CE%AF%CE%BA%CE%BF%CE%BD-%CE%BD%CE%BF%CF%83%CE%B7%CE%BB%CE%B5%CE%AF%CE%B1/%CE%B2%CE%BF%CE%B7%CE%B8%CE%AE%CE%BC%CE%B1%CF%84%CE%B1-%CE%BA%CE%B1%CF%84%CE%AC%CE%BA%CE%BB%CE%B9%CF%83%CE%B7%CF%82/

In the above url in the content you can see 2 boxes which the color is light grey as is the rest content area that is calibrated through colors in costumize/colours/content...

I would want the color inside the box to be white so there isnt difference between the white background of my images and the box, but i dont want to drop the light grey selection in content/colours...

Is there a way to do it?

Thank you in advance!!