Yea, css let's you do the tricks with visited links.
It is possible to use pictures in language menu. Only you have to
follow the certain rules when naming these pictures.
When looping through the languages in menu, link to images with
something like this:
{% for language in site.languages %}<a href="{{ language.url }}"><img
src="/images/flag_{{ language.code }}.png"
title="{{ language.title }}" /></a>{% endfor %}
Now if you upload images with spanish and french flags, respectively,
"flag_es.png" and "flag_fr.png" then these images will be shown in
language menu.
Another way to do this is to use flags sprite, e.g.
https://github.com/lafeber/world-flags-sprite and let css class names
to take care of the rest, in this case your markup code should look
like this:
{% for language in site.languages %}<a href="{{ language.url }}"
class="flag {{ language.code }}></a>{% endfor %}
You are free to remove the design name from the stylesheet path of
your custom design. Edicy uses them to make sure that the correct
stylesheet gets loaded when user switches between centralized designs.
Cheers,
Priit.