In Valve's eternally reliable incompetence, the Points Shop preview of profile mini backgrounds isn't even accurate. The three issues are that the overlay graphics are shown too small, aligned too far to the right, and the bottom cutoff matches neither the playing state nor the non-playing state.

The good news is that it is not too severe of an issue because you can at least rely on the fact that the background image will not be cut off on the left or right. (But it is getting rescaled to a very crude 51% original size in some views. - Others might be smaller.)

So here I will give you comparison images so that you can better estimate what the result will look like. (I made these with manual edits based on checking other people's backgrounds vs. the store since I don't have mine yet, but the points are incoming. Thanks to the anonymous donor!)

The original file
(640x570)




What the Points Shop pretends it will look like
(365x251)




What it actually looks like (playing mode)
(328x266)




What it actually looks like (non-playing mode)
(328x210)

To write a guide for Steam itself instead of a game, use this link:
https://psteamcommunity.yuanyoumao.com/sharedfiles/editguide/?appid=753


Also check out my related guide for previewing the big profile backgrounds:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2401647320

I finally got the points from an award. Had to wait almost the full 14 days, and the notification came only after 7 days.
And I realize that the Steam client's Chromium-based browser adds an intense blur to the lower half that spoils a bit part of the beautiful art, while Firefox browsers (at least my slightly older Waterfox) merely darken it a bit to preserve contrast to the overlay.
Makes me wonder what the excuse is for the name field, which has no alteration but could be interfered with by certain backgrounds, too.

My browser:


Steam client: