a class just for the article-side

hey,

i would like to know if there is any way to add a class to the article-side..

i would like to change:

<div id="main" class="site-main">

into:
<div id="main" class="site-main container">

but just on the site where the articles are listed.

i appreciate any other way as well – i just need to add a container class to the beginning of my articles-listing.

thanks in advance!