Thanks for the tip, Krikor.
Btw, all I had to do was to change line 329 from this:
div class="fb-like" data-send="false" data-width="200" data-show-faces="true"></div>
to this:
div class="fb-like" data-send="false" data-width="200" data-show-faces="true" data-colorscheme="dark"></div>