Hi !

I use MC/CQ to my homepage, I chose one full post above columns and I have 3 columns. For my 3 columns, I would like to display the thumbnail at the top center, and the excerpts centered below the thumbnail.
By default, in Ata 3.7.12 the thumbnail display is left-aligned, and I want to keep this configuration for category pages, but center-aligned only to the home page.

I tried to add this code in the CSS insert area :

body.page-id-2 div.post-bodycopy img.wp-post-image {
display:block;}

but, of course, it does not work (I tried many of 'div name')

I also like the thumbnail of the post above the columns is much larger than columns...

Can you help me or tell me what the name of the div that I need to call in the css ?

Try this css

td.mccq_column1,
td.mccq_column2,
td.mccq_column3 {width: 33%;}

.mccq_column1 img.wp-post-image,
.mccq_column2 img.wp-post-image,
.mccq_column3 img.wp-post-image {
    float: none;
    margin: 0 20% 5px 20%;
}

Wonderful ! My thumbnails are centered! Thank you !
I will increase their size, so that it takes the entire width of each column, but how can I change the size of the thumbnail above the columns?

this is my homepage : http://www.staysimple.fr/

try looking for a plugin that will do like http://wordpress.org/plugins/ajax-thumbnail-rebuild/

Thank you,

It's Ok, Colums have the style what i want, thumbnails have good size !

Now, i want change the css-style of the full post above the colums on homepage without changing the style of others full posts on others pages ( font, img-align ... ) It is possible ?

i want change the css-style of the full post above the colums on homepage without changing the style of others full posts on others pages ( font, img-align ... ) It is possible ?

absolutely. You just have to determine a CSS selector that is specific to that area. There are two ways to do this:
1) use a code examiner like FireBug and look at that post and see what ID's/classes are uses or
2) view the source of the page in your browser and look at teh ID's/classes that are used.

Once you have this you can code a CSS selector and CSS rules that will only apply to that area.