Center an image

I was wondering if I can center a image when I put it up in my sidebar? As you can see on my website here: http://www.djurskydd.nu the Jordbruksverket is more to the left than to the middle. Is there a way to fix that? I tried adjusting it to centre before I put it up but unfortunately it didn’t help.

Every help would be appreciated!

https://wordpress.org/plugins/really-simple-image-widget/