I have been trying to design my new website using CSS. I have been experiencing a small issue. I am getting a blank white space to the right navigation bar. It somehow looks awkward, as I want it to stick completely to the right

Check these codes

#main {
background:#FFF;
float:right;
width:642px;
}
and
#sidebar {
float:left;
width:152px;
}

Am I doing something wrong here

I agree with “shanewarne” – However I would also like to add the following tip.

Try changing your BG colors. Do not add any borders, as it will make your <div> tag wider and mess your float.