Default font in threads and categories/topics

Hi I'm using phpBB2 for my forum and I was wondering,
Is it possible that you can change the default font size of all text on the forum?

For example, the categories and topic titles will always be font size 14 and the content that is written into a thread will also be a default size of 14?

Edit:

Also is it possible that I can edit the Login Popup?
For example I want to change the button Register to something else, is this possible?

Thanks

Code:

.topictitle, h1, h2{
Font-size:14px;
}
.postbody{
Font-size:14px;
}

Add this to your css & check.

Nothing changed , I have also tried using the simple CSS editor and changing the Main, Links and Post and Categories font size to 14 and bigger but there hasnt been any change

Code:

        .topictitle, h1, h2{
        Font-size:14px !important;
        }
        .postbody{
        Font-size:14px !important;
        }

Add this & check.

That works! However the font size of forum titles and descriptions are still smaller, the thread titles and content size have worked fine.


EDIT:

OK I FIXED THAT.
I just need to add in:
<span style="font-size: 14px; line-height: normal"> title or description </span>.

Now as i mentioned before, with the login popup, is it possible for me to edit this in any way? I want to change one of the buttons , can this be done?

Code:

.genmed {
Font-size: 14px !important;
}

Add this to your css.

Also, to change the size of the forum font titles.
General>Categories and Forums
Click on a forum name & edit.

Code:

<font size="3">Forum Title</font>

Awesome, thats great!

Now as i mentioned before, with the login popup, is it possible for me to edit this in any way? I want to change one of the buttons , can this be done?

I am afraid, its not possible. Sorry.

Aww okay, no worries, thank you very much for your help!