I can sort of see what they mean by appearance, but its not far off looking tidy. The issues are mostly around padding and UI element proportions. Some of your

I can sort of see what they mean by appearance, but its not far off looking tidy. The issues are mostly around padding and UI element proportions. Some of your icons are too large for the elements they are inside of, the scaling of form elements within your filter interface is somewhat inconsistent too. If I wasn't completely slammed at work I'd be open to submitting a PR.