If I understood you correctly, You should try analysing the HTML and changing the related CSS classes.
yes, i have tried to override the CSS, but it only can change the format, but not remove the space
Did you check where the space come from?
If you inspect the page with your browser's Developer tools extension (the name maybe is different but they all have it now), what do you find where you have the spaces?
If you have elements there, even if empty (like a <div> or things like that) of course they "take some place" in the page, but if you manage to uniquely identify these things with CSS you can fix the thing.
Also maybe post a screenshot to show exactly what/where your issue is ... will maybe give people a different idea on how to solve it.
It'll be a combination of padding and cellspacing and perhaps widths/stretching. All overridable through CSS.