Hi!
As your CSS is being cached and minified its not immediately apparent to me which rules might be (cached copies of) old rules and which might be custom rules, but in any case you should be able to resolve this by adding a CSS snippet like this one:
.tribe-events-list .tribe-events-event-image img {
float: left;
margin-right: 20px;
width: 200px;
}
This might go in a tribe-events/tribe-events.css file within your theme directory, for instance (but see our Themer’s Guide for complete details) – and remember to flush the cache once you’ve added it!