Sorry it's so small ugh
Apart from the fact that the text says that I'm getting this achievement for 100 vends, this is actually my ten thousandth vend. But that's not the issue at hand- the issue is that I received this achievement and tried to keep vending but the achievement covered up my most recent vends, and as I continued to vend, the box that the achievement was in started stretching, always covering the vends that happened after I unlocked the achievement, and the small picture of the vending machine related to the achievement was moving steadily to the right....
It's able to be solved by just leaving the page and coming back (or refreshing) but it's still inconvenient and probably not supposed to happen. I don't think this is related to my customcss since most of my custom css is just color changes (as large, stark white backgrounds hurts my eyes).
Did this happen to anyone else?
That happened to me earlier last week when I got 20k vends.

Yep, it happened to me yesterday. I think you just have to change pages and come back and that's really all you can do about it :/
Also, all the tiered achievements will give the lowest tier* in the blurb when you reach a new tier -- every time I get a new quest achievement it still says "Complete 5 quests for Quentin!" or whoever I'm doing them for when I've done about a thousand or more of each.
*I actually think it might be "lowest tier when the achievement was first created" because I've had it show up as "Do 5 of something!" when there's a "1" tier, but I'm not sure.
This happened to me too. I found it quite amusing for some reason.