Horizontal Spacing with HTML 5

[KeredDrahcir]

I have a website coded currently in XHTML and I recoding it in HTML 5. There a few spacing issues that need to be sorted out in order get it to look the same.
I'm replacing most of the inline-block with block if I can get it to look the same and setting the vertical align on images to something other than baseline.

The only problem I'm having is some elements of the page have a bit of horizontal spacing on them. One page had the image about a pixel or maybe half a pixel to the left and the same applied to some text in a table, some of my list and some other content and buttons.
It's not global and I don't know why it's there and only affecting some elements.
Is this a known issue?

The alignment on the two right columns is a bit out.

 
ul {
    list-style:none outside none;
    margin-bottom: 15px;
}
 
ol {
    margin-left: 20px;
    margin-bottom: 15px;
}
 
ul li ol, ul li ul {
    margin-bottom: 0;
}
ul li {
    padding-left:0;
    font-family:verdana, arial, sans-serif;
    font-weight:normal;
    font-style:normal;
    text-decoration:none;
    list-style:none;
}
.third-column {
    float: right;
    padding: 0 10px 0 5px !important;
    width: 336px;
}
 

If I take out the padding on the third column style, it shows the same. Why is HTML 5 interrupting the padding differently?