Okay, so by putting the
example.com/blog/wp-content/themes/default/style.css
that shows there are no permission problems in accessing those files. That should be true for all your theme files, but ideally you would want to run that test again with whatever theme you're trying to use.
Now let's find out which CSS files your page is actually using.
Use the View Source function to look at the actual code being sent to the browser. In particular, look to find stylesheet references in the form
<link rel='stylesheet'.....>
Is it referencing the correct stylesheets.
Are the paths defined correctly? In other words, if you take the path from the stylesheet reference and put *that* in your browser (adding the domain name if necessary), does it bring up the right code?
So in my case, I have all stylesheet links as absolute links (i.e. including the domain), so I can just paste that in.
Another way to do this is to use Firebug to see what stylesheets are being invoked. Firebug is the web developer's best friend. It's a plugin for the Firefox browser that lets you troubleshoot all sorts of problems and even edit CSS on the fly and play with new design ideas without changing any files.
So if you're going to be playing with your CSS, you'll want to start by downloading and installing Firebug on your Firefox browser.
[
getfirebug.com...]
Restart FF, make sure Firebug is installed. You should have a little bug icon in the bottom right bar of your browser and you should also have a full FB menu under Tools -> Firebug in the main browser menu.
Now navigate to one of your blog pages.
Once the page loads, click on the little bug in the bottom bar or select Tools->Firebug->Open Firebug
You'll have a split window now with FB on the bottom. You'll see an arrow pointing into a box and then tabs named Console, CSS, Script, DOM, Net.
If you go to the CSS tab, it will have a dropdown menu that will tell you all the CSS files that are loading for the current page.
If you select the arrow pointing into the box, that's "Inspect Element". Click on the arrow and then hover over elements on your page. It will outline them as you do and will reveal the HTML and CSS defining those pieces of the page. Click on one and it will "freeze" there. Now you can see which styles are being invoked for that piece.
Are they the ones you expect?
So once you've done these steps, you will have a sense of where the problem is occurring and then you can work backwards from there.