Revert "css: size the agent picker's tab marks inside prose"

This reverts commit 942f543.

Superseded on main by #5719, which fixed
the same thing more generally: the offending
.prose:not(.prose-natural-size-images) img rule now sits inside
@layer components, and an unlayered rule beats any layered one whatever its
specificity, so .ff-agent-tab img wins on its own and every other component whose
unlayered styles that rule was outranking is fixed too, not just this one.

The picker only looked broken here because this branch predates that change.

Author: dimitrieh

src/css/style.css

@@ -3899,20 +3899,3 @@ lite-youtube::before {
         transform: none;
     }
 }
-
-/* The agent picker's tab marks, inside prose.
-
-   The .ff-agent-tab img rule further up moved the sizing out of utility classes
-   precisely so .prose could not beat it, but it is not specific enough to finish the
-   job: the site's own `.prose:not(.prose-natural-size-images) img` is 0-2-1 against
-   that rule's 0-1-1, so in a blog post, changelog entry or docs page the marks get
-   width:100% and height:auto back. Being flex items in an auto-width button, the
-   100% cannot resolve against anything, so each mark falls back to its intrinsic
-   size: the ChatGPT glyph is 780px square in its own file and renders at that.
-   /ai has no .prose wrapper, which is why the picker looks right there and only
-   there. Matching .prose's own specificity and sitting later in the file takes it
-   back. */
-.prose .ff-agent-tab img {
-    height: 1rem;
-    width: auto;
-}