Probably the biggest visual change this week is that we now have spacers in
the toolbar <https://bugzilla.mozilla.org/show_bug.cgi?id=1383009>. These
help to separate the location bar from the other utility buttons, and also
keep the location bar relatively centered within the window. We have also
replaced the bookmarks menu button with the Library button (it’s the icon
that looks like books on a shelf).
Changing to Compact density within Customize mode changes the toolbar
buttons to now use less horizontal space. The following GIF shows the theme
changing from Compact to Normal to Touch densities.