Here's a snippet of text from the ePub:
Code:
<p class="calibre3">Nulla viverra viverra odio, ut euismod arcu ultrices ut. Sed laoreet blandit turpis quis dictum. Donec rutrum tellus at nulla aliquet feugiat consectetur sem suscipit. Suspendisse non turpis mauris.</p>
<h2 class="calibre4">Lorem ipsum dolor sit amet, consectetur adipiscing elit</h2>
The relevant CSS parts are:
Code:
.calibre3 {
display: block;
font-weight: normal;
margin-bottom: 1em;
margin-left: 0;
margin-right: 0;
margin-top: 1em;
text-align: justify;
text-indent: 1.1em
}
.calibre4 {
display: block;
font-family: sans-serif;
font-size: 1.5em;
font-weight: bold;
margin-bottom: 0.83em;
margin-left: 0;
margin-right: 0;
margin-top: 0.83em;
text-align: left
}
I notice that the bold style (calibre4) is set to align left, whereas the "normal" style (calibre3) is set to justify. Also, I note that Calibre seems to have interpreted the bold parts from the original source as being headings, which might explain the different CSS.
However, I don't know why this is so. I'd suggest you wait for someone more knowledgeable to show up.