Add nice overlay on banner

[benoit74]

When no banner image is used, only a single color is used. When color is white or close to white, it makes a weird gradient.

In some old browsers, the gradient does not even load.

It would be nice to have some kind of overlay pattern to make the banner visible in all situations and limit the "weirdness" of this part of the UI under all circumstances.

[dan-niles]

I tried a couple of backgrounds from https://www.magicpattern.design/tools/css-backgrounds. I like the first one. @Popolechien @benoit74 WDYT?

Wavy:

Zigzag 3D:

Isometric:

Polka:

[benoit74]

How do they work with "white on white" (which is the main concern as far as I've understood).

For now, my preference order is : isometric > zigzag > wavy > polka ; polka is not visible enough ; wavy is a bit too weird, difficult to know it is an intended pattern or a display bug

[dan-niles]

Wavy:

Zigzag 3D:

Isometric:

Polka:

[benoit74]

What we've agreed in our daily meeting is that we will go with zigzag for now. Could always easily be revisited if someone has strong arguments for something else.