Pure Acrylic (Firefox 138 and newer)

[QNetITQ]

Enable Acrylic in your browser and add the code below.

/* ---------- Acrylic background ---------- */

@media (-moz-platform: windows) and 
        -moz-pref("widget.windows.mica.toplevel-backdrop", 2) and
        -moz-pref("extensions.activeThemeID", 'default-theme@mozilla.org') and
        -moz-pref("browser.tabs.inTitlebar", 1)
{
    :root
    {
        background-color: transparent !important;
    }
}

[kocane]

Looks pretty nice with a mix of dark and light mode

I do still miss Aero though.