For the first two errors, you should have <style type="text/css">
instead of just <style>
:
<STYLE type="text/css"><!--
.qa-body-js-on .qa-notice {display:none;}
//--></STYLE>
and
<style type="text/css">
#qa-share-buttons-container {
background: none repeat scroll 0 0 #DDDDDD;
font-size: 125%;
font-weight: bold;
margin: 20px 0;
padding: 20px;
text-align: center;
}
..
</style>
For the last error, as stated by the validation output:
Another possibility is that you used an element which requires a child element that you did not include. Hence the parent element is "not finished", not complete.
In this case, your <ul>
node starting at line 1182 is just:
<UL CLASS="qa-nav-footer-list">
</UL>
You will need to add some children to the unordered list.