Firefox pwa.md

Create new firefox profile for pwa:

• firefox -P then on gui add a new profile named "app"

reference
Before we edit/create userChrome.css, we first have to make sure it is enabled.
userChrome.css is by default disabled on firefox >= 86:

• in about:config set toolkit.legacyUserProfileCustomizations.stylesheets to true to enable userChrome.css

reference
Edit/create userChrome.css:

• cd ~/.mozilla/firefox/*.app/
• mkdir chrome
• vim chrome/userChrome.css and set content to something like this:

/*
 * Do not remove the @namespace line -- it's required for correct functioning
 */
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to XUL */

/*
 * Hide tab bar, navigation bar and scrollbars
 * !important may be added to force override, but not necessary
 * #content is not necessary to hide scroll bars
 */
#TabsToolbar {visibility: collapse;}
#navigator-toolbox {visibility: collapse;}
browser {margin-right: -14px; margin-bottom: -14px;}

Now you can create your shortcut that runs e.g. firefox -P app netflix.com