Main Body Content Overlaps Sidebar

I’m using the Twenty Sixteen theme for one of my sites.

For some odd reason, my responsive ad units are too wide, but only when using this theme. They extend from my main body content all the way across (and actually under) my sidebar, despite being responsive in size.

This only happens in Safari, and only on desktop as far as I can tell. You can compare Firefox/Chrome to Safari to see the difference.

It also fixes itself if you reload the page in Safari.

Thanks for any help!

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