Mini FrontPage how to center thumbnail

I would like to center the tumbnails using mini frontpage

www.colegioalazne.com/joomla32/

Thanks in advances

Hi
I added your code but the tumbnail appeared not clear. Finnally, I changed your code so:

.minifrontpage-default .mfp-table-cell-inner .mfp-img-left {
float: none;
margin: 0px 10px 10px 25px;
display:block;
width:80%;
}

and I chanched the thumbnai's size (350 x 200) and it's perfect.

Thanks