Content going full width even though container is not

From a quick look, the contact form fields are centered, with a left and right column. This is on a laptop display; didn’t check other devices.

But, the best way to diagnose this is with the Developer Tools. Right-click your form area, select “Inspect Element” (or whatever or F12), then poke around looking at the CSS that is being used for the various elements.

Note that this place is not for CSS-type questions, it’s for WordPress development; not plugins, not themes, not CSS, not JS, not PHP. It’s best to post your question in the appropriate Stack Overflow area….you’ll get faster/better answers there.