Kaptinlin Themes Support

I'm using shortcode to display my portfolio. I want the portfolio items to line up like
[item A][item B][item C]

but on firefox the last item will always end up a new line, like
[item A][item B]
[item C]

The best way I can come up with to fix it is to add a final "dummy item" at the end of the list so that at least all the items I want will end up on one line.

My website is www(dot)lrccoins(dot)com
The portfolio I''m talking about is on the front page.

I tried adding this css to the header but didn't help:

li.portfolio_item
{
display:inline-block !important;
position:relative;
}


Forgive me if this issue is already covered somewhere :/