Fix distorted avatars

The avatars in the thread view of this forum are not square as they should be, but they’re distorted (45x48px instead of 45x45px).

Screenshot 2023-10-24 at 15.36.12

The reason seems to be a custom addition to the theme stylesheet of this forum.

img {
    max-width: 90%;
}

I assume someone wanted to modify the display width of inline images or something like this and was not aware that this will be applied to avatars, too.

Anyway it would be nice if someone could either remove this tag selector, or replace it with a reset like this:

.avatar {
    max-width: unset;
}