Atahualpa is a wonderful theme. You can do almost anything. Still, I just cannot find out how to change the size of the diverse headings in pages and post. Where do I do that?
What I mean is, I only want to make the headings smaller compared to the normal text, which should be the same size.
Tried to change in css.php, but that didn't do it.

Look at the theme options

That's where I started looking of course, but either I am blind or it's not there.

ato->Style Post & Pages

Hmm... The closest I got here was this:

"BODY Box
Style the box that contains the post/page main text (= the "body copy"). The text and links in the post/page main text box can be styled on the main tab "Text & Link Styling"."

But the main tab "Text & Link Styling" appears to be about something else than headings, provided of course that I am not supposed to insert new code for headings here. But this should not be the case. The existing headings are pre-formatted and it should be possible to change the formats.

In the Style Posts and Pages section there are boxes for styling headlines on post and pages.

What I want to change is not the headlines (or bylines) of the pages (one for each page), but all the headings namned "Heading1", "Heading2" etc inside the text.

Please post a URL point to an example or screen shot circling the issue

Basically, I want to chage this:

h1 { font-size: 34px; line-height: 1.2; margin: 0.3em 0 10px; }
h2 { font-size: 28px; line-height: 1.3; margin: 1em 0 .2em; }
h3 { font-size: 24px; line-height: 1.3; margin: 1em 0 .2em; }
h4 { font-size: 19px; margin: 1.33em 0 .2em; }
h5 { font-size: 1.3em; margin: 1.67em 0; font-weight: bold; }
h6 { font-size: 1.15em; margin: 1.67em 0; font-weight: bold; }

into this (some further adjustments may be needed);

h1 { font-size: 22px; line-height: 1.2; margin: 0.3em 0 10px; }
h2 { font-size: 18px; line-height: 1.3; margin: 1em 0 .2em; }
h3 { font-size: 15px; line-height: 1.3; margin: 1em 0 .2em; }
h4 { font-size: 13px; margin: 1.33em 0 .2em; }
h5 { font-size: 1.3em; margin: 1.67em 0; font-weight: bold; }
h6 { font-size: 1.15em; margin: 1.67em 0; font-weight: bold; }

You can find those in ato->add HTML/CSS Insert->CSS Inserts option
however if you want to just change the post/page titles you want to use ato->Style POSTS & PAGES->HEADLINE Box: xxxxxx

Thank you very much! Now I got exactly what I wanted in the ato->add HTML/CSS Insert->CSS Inserts option!