buttons don’t change size

Hello,

I was working on my webpage yesterday and created a new page. To this page I added an inner paragragh with thre columns. To each column I added a photo and a button. While the photos show in the correct width, the buttons are all just a little bit wider than the text written on them. But I wanted them to be the same width as the photos: i.e. the full width of the column. Somehow I can’t change their sizes. Even when i click on “extra-big” or “extra-small” for the button-size there is almost no difference at all, not even in the editor window.

Can anyone help me with this issue?

Thanks a lot to the community.

The page I need help with: [log in to see the link]