Website In Firefox Is Distorted

You may have come across a rendering issue. This used to be more common- it's a question of
a. whether the site is properly designed
b. browser conformance to a standard (question- is there in fact any one standard?)
Is your site web standards-compliant?

Best forward a comment to the site owner/support and check.

I tend to think it's up to the publisher to try to ensure compatibility with at least major browsers. There are services which allow rapid comparison, but it would then be up to a real human to judge the outcome. E.g.
Try A Better Testing Experience For 7 Days | CrossBrowserTesting

For comparison, to eliminate extraneous effects, try FF in its safe mode. (If unsure what that means, see my signature).

I don't use Firefox much these days but I noticed that if you override font settings it can cause the problem.

Reset fonts in firefox to default: