[UI] Increase selected option contrast

[victor-torres]

It's not clear to some people if they really voted for a proposal. The contrast seen may be improved.

Possibilities:

• use different colors
• change background color
• use borders and/or boxes

How it is today:

[victor-torres]

The contrast may be obvious for you, but for some people with special disabilities and some underpowered devices and their poor screens, the story may be different.

Anyway, this is just a suggestion.