class conditional on URL parameter
I have a hard coded search on a page using a URL parameter as follows:
<a class="current" href="index.php">All</a>
<a href="index.php?S_application=Air%20Flow%20Management">Air Flow Management</a>
<a href="index.php?S_application=Splash%20Shield">Splash Shield</a>
<a href="index.php?S_application=Squeak%20and%20Rattle">Squeak and Rattle</a>
<a href="index.php?S_application=Cushion%20and%20Protection">Cushion and Protection</a>
<a href="index.php?S_application=Aesthetic%20or%20Cover">Aesthetic or Cover</a>
<a href="index.php?S_application=Acoustic%20Insulation">Acoustic Insulation</a>
<a href="index.php?S_application=Gasket%20or%20Seal">Gasket or Seal</a>
<a href="index.php?S_application=Other">Other</a>
As you can see, the default page I have the A tag with a class of "current" that highlights that link. I'd like a simple way to include the class on each A tag automatically or defaults to tagging the "All" A tag when there is no URL param included. So in other words, when a user clicks on "Splash Shield", that link is automatically tagged with the class "current". How would I do this?