Fixed width layout, inaccessible fixed metric (px) fonts, illegible colour contrasts -- the trifecta of /FAIL/ at web design. NOT an encouraging start to what's supposed to be webmaster tools.
Under the hood it has tables for nothing, tables for layout, and nothing remotely resembling semantic markup or a properly built form! You seem to have some form of content cloaking going on (either that or broken tooltips?) which is guaranteed to get your site slapped down for abuse by the search engines, and on the whole it's a laundry list of how not to build a website.
EVEN IF using tables for layout, you've got TD+H2 doing CAPTION's job, TD doing either TH or LABEL's job, H1 on an element it's unlikely the sidebars are subsections of, and tags like CENTER and FONT that have no business being used on a website any time after 1997.
... though that last part does an excellent job of proving what I'm always saying about HTML 5's target audience; that being it seems crafted for the people stuck in the late '90's and isn't for anyone who embraced HTML 4 STRICT, separation of presentation from content, semantic markup, progressive enhancement, or the dozens of other improvements of the past fifteen years.
I mean, you don't even have MEDIA targets on your stylesheet LINK!
I would throw it out, redoing it with semantic markup, in a semi-fluid elastic responsive layout. I'd probably also swing an axe at the GA nonsense since anyone qualified to make a 'webmaster tools' should be able to glean the same data from the server logs with tools like Analog or Webalizer... at the very least move the script out of HEAD and right before </body> so it can start loading sooner.
Hmm, I'd include how I'd have done the markup for that page, but it would blow past the post size limit. Tell you what, I'll toss together how I'd have written / designed that same page and toss it up on my server (don't worry, behind a robots.txt so I don't steal your link mojo) if I have time today. (something to do while everyone is over here getting readt to watch tonights WWE PPV).
Just to give you a small taste though:
<div id="top">
<h1>
<a href="/">
DOMAINFOCUS
<span>-</span>
<small>Free Webmaster Tools</small>
</a>
</h1>
<ul id="mainMenu">
<li><a href="/index.php">WEBMASTER TOOLS</a></li>
<li><a href="/favicon.php">FAVICON GENERATOR</a></li>
<li><a href="/integration.php">SITE INTEGRATION</a></li>
<li><a href="/contact.php">CONTACT</a></li>
<li><a href="/about.php">ABOUT US</a></li>
</ul>
<div id="contentWrapper"><div id="content">
<h2>Domain Tools</h2>
<form action="results.php?s=whois" method="post">
<h3>DOMAIN WHOIS LOOKUP</h3>
<fieldset>
<label for="whois_domain">Domain Name:</label>
<input type="text" name="in" id="whois_domain" placeholder="domain.com" />
<input type="submit" class="submit" value="Go" />
<div>?<div>
<p>
This tool allows you to find the contact information for the owner of a domain name. It is also useful for determining if a domain name is currently taken or available for registration.
</p><p>
Please keep in mind that some information may be limited due to the specific registrar the domain has been registered through. A link for more information can generally be found within the whois results.
</p>
</div></div>
</fieldset>
</form>
