Hi Chris,
In the case of that particular page the issue is just that the page content is all in a table. The table will not compress naturally.
This CSS will fix it so that all of the table content is visible on a phone:
.art-article table, table.art-article { max-width: 100%; }
Unfortunately that solution can result in table content looking "squished" sometimes (it really depends on the content). If you just want the user to be able to scroll, you can add this CSS instead:
.table-wrap { overflow-x: auto; max-width: 100%; }
And then in your HTML, wrap your table with a div with the class "table-wrap", like this:
<div class="table-wrap">
<table>
...
</table>
</div>
Hope this helps!