Make the Alt Styles list less tall on large screens

On the small-screen layout, the popover goes down and covers the item
list, which isn't a big deal in context; so I want it to be basically
as tall as it can be without being unwieldy, to give more info.

But on the large-screen layout, it doesn't take long at all for the
popover to start intersecting the pet preview, because it *has* to go
up and cover the pet preview. So, I'm much more reserved about how much
vertical space I'm willing to give it!

(I also considered sending the popover off to the *right* of the button,
to cover the item list, but it felt *way* too weird imo! Especially in
the expressions case.)

app/javascript/wardrobe-2020/WardrobePage/PosePicker.js

@@ -679,7 +679,7 @@ function StyleSelect({
       as="form"
       direction="column"
       gap="2"
-      maxHeight="40vh"
+      maxHeight={{ base: "30vh", md: "10rem" }}
       padding="4px"
       overflow="auto"
     >