Browsing kde.org/index on a mobile, the text on top of the banners gets partially bad to read because parts of the background image do not have contrasts to the text color (see the group picture of "Join the game" banner, but also "Plasma 5.9" and "Slimbook" on small screens in portrait/landscape mode run the risk of words/letters having improper background). Just reporting, properly protecting against this surely heavily interacts with design ideas, so I better leave that to the experienced and do not try proposals :)
The banner was removed so the problem doesn't exist anymore :)