When you place a variable in the snippet call, it is automatically avaliable in the snippet.
Example
[!GetLink?id=2&title=Page Title&css=style1!]
In the snippet, if you have a variable used that was in the snippet call like this...
$output = "<a href='' title='$title' class='$css'>$title</a>";
return $output;
This will return on the page
Quote
<a href='' title='Page Title' class='style1'>PageTitle</a>
There is no additional code required unless you want to start adding default values if one value is missing or other conditional changes and tweaks to the output.
This is where you use something like
if(!$css) $css='defaultStyle';
Then define your css in your css file as normal.
I hope I have understood your question.