Website not working properly

I am having problems with the site I have created: The thing is that on the computer I am working with it looks fine, however, in other computers looks different. Things are not were should be and appear like a white square around some of the items when on my computer don’t. Could you please help me?
Thank you very much in advance.

I already fixed by adding code but anyway it looks like there is by default on some place I don’t know.