How to make a table wider in Google Docs

I’ve spent a frustrating couple of days trying to squeeze things into a Google Docs table that was too narrow for its content.

The problem was that while I could move individual columns within a table, I simply couldn’t find the way of widening the outer boundaries of the table—i.e. moving the leftmost border to the left or the rightmost border to the right. Making things worse, I had been able to do it a couple of weeks ago. But nothing I was doing seemed to work now.

The trick turned out to be remarkably easy, though it points to a UI problem in Google Docs. Basically, Google Docs allows you to adjust column width in two different ways: by reaching up into the measurement ribbon at the top of the document and moving columns there (when you do this, you see a left-right arrow cursor [⇔] that has not been captured in the screenshot):