Add possibility to zoom keymap and persist that in settings

[astrolemonade]

Hey! I am trying to use the keymap to learn a new layout and I find the keymap display too small.

I managed to add CSS instruction to the whole container of the keymap:


The only issue is that this setting is not persistent. Can it be added to the settings? I know that many other keymaps would benefit from this.
Thank you!

[astrolemonade]

PR implementing this change: #5659