Order-changing Sidebar
Mixing Flexbox and Floats? An abomination!!
Flexbox is used here on small/mobile size to display the items in a different order than source order.
Floats are used on larger/desktop size to make the items form a sidebar.
It also uses some pseudo-element and overflow trickery to fake the same-height columns for the floats. Go ahead, add way more content to this main area, or add another sidebar item. I dare you. (Ok, but don't get, like, carried away with it, maybe.)
Why??
Basically, flexbox itself was not cutting it for design needs here. Unless I'm clueless and there's a way. In that case: PLEASE SHARE! (Note: solution must allow for any quantity of sidebar items and no known or fixed height of said items)
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