Rows with Layout Builder in Columns don’t collapse responsively

If there is a row with 2 or more columns, we know they stack when browser width shrinks. But if there is the Layout Builder widget (the one that let’s you create rows/columns inside of columns) – for some reason the columns that house that layout builder won’t go full width and stack – they just stay in split columns.

Here is an example project: mypayjunction.com

The blue section under the header is a row. The text/button is one column on the left, and the stamp graphic is another column on the right. The text on the left has the Layout Builder plugin to create those additional columns.

When you shrink the browser, the text on the left should stack and the graphic on the right should go under in it’s own row. However, it doesn’t – both stay side by side.

I’ve looked through the CSS and can’t figure out why, since it shows that the column each have 100% width, but are not exhibiting it.