Nelson<p>As Mozilla fumbles <a href="https://jawns.club/tags/Firefox" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Firefox</span></a>, let's reflect on what we'd lose if this unique browser + engine dies.</p><p>How can I get a list of <a href="https://jawns.club/tags/HTTP" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>HTTP</span></a>, <a href="https://jawns.club/tags/HTML" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>HTML</span></a> and <a href="https://jawns.club/tags/CSS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>CSS</span></a> features that are only supported by Firefox / <a href="https://jawns.club/tags/Gecko" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Gecko</span></a>? Does caniuse.com or MDN have this? Wikipedia?</p><p>Only Firefox supports assigning <a href="https://jawns.club/tags/stylesheets" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>stylesheets</span></a> through HTTP headers:<br><a href="https://meiert.com/blog/prefer-http-headers/" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">meiert.com/blog/prefer-http-he</span><span class="invisible">aders/</span></a></p><p>Only Firefox supports alternate stylesheets: <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Attributes/rel/alternate_stylesheet" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">developer.mozilla.org/en-US/do</span><span class="invisible">cs/Web/HTML/Reference/Attributes/rel/alternate_stylesheet</span></a></p><p>Put these facts together, and you can make a secret stylesheet only for Firefox users.</p>