The "text-indent" CSS attribute is how you control the indentation in the first line of each paragraph. I have absolutely no idea how Kindle's converter will handle that css, though. I've never used it. I assume you're talking about sending HTML files to your Kindle's email address and having them convert the files for you?
To eliminate the indentation and make it flush with the other lines, just add the "text-indent:0;" to your existing css:
Code:
p.MsoNormal, li.MsoNormal, div.MsoNormal {
margin-top:0in;
margin-right:0in;
margin-bottom:12.0pt;
margin-left:0in;
text-align:justify;
text-indent: 0;
font-size:10.0pt;
font-family:Georgia;
}