I’m sorry not to be the bearer of better news, there isn’t a way to do this.
The layout options available are 1 or 2 column, and I can see you have two column set up already. It is then possible to hide or show some elements but not resize, which I can see you’ve done as well!
Exactly what I was thinking, you wouldn’t want to be messing with the css each time – better to be building the site!
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