I'd appreciate help to understand why the top margins (or padding?) on Pages and Post pages are wider than my home page.

Compare the following:
Home page -- http://www.joanko.net/. This is my preferred margin (or padding) layout

Page -- http://www.joanko.net/about. There is more space in the header above the blog title. I think there may be more space above some other header elements too compared to the home page. I'm not sure.

Posts page -- http://www.joanko.net/2013/01/legally-obliged. This has the same problem as the Page above.

I've tried a changing a few things in the options. If it helps, here is what I have at the moment.

Body style
padding-top: 30px;

Layout container style
padding: 35px;

Logo image: styling
margin: 0 40px 0 0;

Blog title
margin-top: 20px
margin-bottom: 20px

Blog tagline
padding-top: 10px;
padding-bottom: 20px;

Search box
padding: 0 0 0 0;

Center column style
padding: 10px 100px 10px 10px;

Right sidebar style
padding: 30px 10px 10px 10px;

Post container
margin: 20px 0 70px 0;

Sticky & Kicker
All defaults

Headline box
margin: 10px 10px 0 0;

Headline box: text
padding: 0;
margin: 0;

Is there any other code that I can tell you that would help you figure out my question?

Thanks a lot.

the reason is that on the main page, the title is an H1 and on the other pages it is an H2 and there is different CSS for H! vrs H2

take a look at the 'CSS inserts' option

That's fantastic -- thank you!

I must have copied in the example above the CSS inserts box without thinking about it.

You're a champion.