Improve optics in tile maps with age coloring

[Oi-sin]

Currently the coloring by age of tiles is hardly visible:

• the colorful background map 'hides' the color of the tiles -> make other map types available, eg any of the gray-scale maps available online
• borderlines are too thick and dominate when zooming out

Examples:

[martin-ueding]

Yes, a grayscale map would greatly improve the situation. I already have an idea how this can be implemented.

Decreasing the border should be straightforward.

[martin-ueding]

I've added a grayscale tile layer there. And now it looks much better! I've also decreased the border weight from 1 to 0.5. Is that better now?

[Oi-sin]

Definitely looks better, especially when zoomed in. Thank you!