Hi,
This means that you're missing the new CSS we've added for the backend.
Check the "backend CSS" setting under the Display tab of the HikaShop configuration page.
I suppose that it's not set to "default" as you must have added some custom CSS to your backend.
And thus, your version of the backend CSS file doesn't include the new CSS we've added since you added your customization.
You would have to go back to "default, and then copy your modifications to that new version of the backend CSS file to get the new CSS and get your modifications at the same time.