Hi, yes for those kind of customizations you need to use CSS either in your custom.css file of your template (check template documentation) or you can use custom CSS for images. See: Exposer Config --> Grids --> Image Settings --> Custom CSS. "margin-top:4px; margin-left:auto;margin-right:auto;" should do the trick.
But in your case i think you are talking about the econa images, right? ;-)
For that add this custom CSS Code to your template:
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