PHP generated inline CSS query

I’ve borrowed some code from this support forum so that I can generate an inline CSS style for the specific page a person is on. The navigation button is highlighted depending on what page of the site you’re on. I use this code to style the specific list element using inline CSS:

<?php
if ( is_home() ) { $current = 'b-home a'; }
elseif ( is_page('about') ) { $current = 'b-abou a'; }
elseif ( is_page('about-the-author') ) { $current = 'b-abou a'; }
elseif ( is_page('about-the-site') ) { $current = 'b-abou a'; }
elseif ( is_page('brief-resume') ) { $current = 'b-abou a'; }
elseif ( is_page('archive-index') ) { $current = 'b-arch a'; }
elseif ( is_page('links') ) { $current = 'b-link a'; }
elseif ( is_page('contact') ) { $current = 'b-cont a'; }
?>

<style type="text/css">
li#<?php echo $current; ?> {
color: #fff;
font-weight: bold;
background: #62C061 url(/img/nav-focus.gif) repeat-x bottom left;
}
</style>

As im no expert on PHP what and where do I add to this code to style my list elements if $current is none of these options/pages. eg. a comment page? I dont want any of my navigation buttons highlighted on most of the other pages so the site actually works correctly as it is – the only problem is it wont validate. Basically that means i only need the inline CSS on my main web pages.

Hope that makes sense to someone! Thanks in advance!