Thanks for the quick response.
A new CSS file was created, but the posts are still shown as a vertical list on the page.
This is the CSS:
div.upl-list form, div.upl-list p { margin-bottom: 1em; }
div.upl-list form img { display: inline; padding-left: 1em; padding-right: 1em; box-shadow: none; vertical-align: middle; border: 0 none; }
div.upl-list ul { list-style: none outside none; overflow: hidden; margin-left: 0; margin-right: 0; padding-left: 0; padding-right: 0; }
div.upl-list ul li { margin: 0 0 1.5em; clear: both; }
div.upl-list ul li:last-child { margin-bottom: 0; }
#upl-list-1922 ul li img { width: 75px; height: 75px; display: inline; float: left; margin: 0px 8px 8px 0px; }
#upl-list-1922 ul li { margin-top: 0px; margin-bottom: 24px; margin-left: 0px; margin-right: 0px; display: inline-block; vertical-align: top; width: 100%; max-width: 75px; }
I use the Twenty Twelve theme.