/* ==UserStyle==
@name           Mastodon - Hide All But First Pinned Post
@namespace      github.com/pixeldesu/userstyles
@version        1.0.0
@description    Hide each pinned post except the first one on user profiles on Mastodon
@author         pixeldesu
==/UserStyle== */

@-moz-document domain("your-mastodon-instance-url-here.com") {
    article[data-id^="f-"]:not(:first-of-type) {
        display: none;
    }
}