The Joomla 2.5.* version of the Web Links Component is missing a class for the descriptions in the list view of a category. This means you can't control the look of the description using css. To fix this you can do a simple template override.
First of all, locate the file
Create in your template, in the HTML directory the following subdirectory structure:
and copy there the above file. Now open the file, and locate this line (around line 131, depending on your exact version:
<?php if (($this->params->get('show_link_description')) and ($item->description !='')): ?> <?php echo $item->description; ?>
Replace the second line with this:
<div class="weblink_desc"> <?php echo $item->description; ?> </div>
Save the file. Now you can style your description by adding to your template's CSS file something like:
font: 14px bold "Verdana";
Hey, you just created a new template override! Don't tell me, that wasn't easy! Enjoy it!