
Make It Disappear
<style type="text/css">
.leftnav { display: none; }
</style>

Borders
To remove the border from the leftnav, use:
<style type="text/css">
.leftnav, .leftnav td { border: none; }
</style>
To change the border style instead:
<style type="text/css">
.leftnav { border: 1px solid red; }
.leftnav td { border: none; }
</style>
Nb, the
border: none; part of this code is deliberate, as the leftnav table also
has an inner border which would still show up otherwise.
[ More Border Styles ]

Background
To set a background color for the whole menu:
<style type="text/css">
.leftnav { background: red; }
</style>
Or a background image:
<style type="text/css">
.leftnav { background: url('http://www.PATH TO YOUR IMAGE.gif'); }
</style>
More on
[ Backgrounds ]

Text Styles
To change the plain (none linked) text bits:
<style type="text/css">
.leftnav, .leftnav table { color: red; }
</style>
To change the links (and hover links separately):
<style type="text/css">
.leftnav a:link, .leftnav a:visited {
color: red;
background: navy;
font-size: 8pt;
}
.leftnav a:hover {
color: orange;
background: green;
font-size: 8pt;
}
</style>
More
[ Text Styles ]

Size
You can give your leftnav table an explicit width (height also works, but because .leftnav refers to more
than one table, you probably don't want to set height for it, if you want to know why, try it and see).
<style type="text/css">
.leftnav { width: 200px; }
</style>

Positioning
To flip your leftnav over to the other side of your profile, the code is:
<style type="text/css">
.main, .maintop { direction: rtl; }
</style>
You can also use margins to shove it a bit to the right:
<style type="text/css">
.leftnav { margin-left: 50px; }
</style>