Previously, when hiding the settings overlay, it remains to have a width
of `56` (sidebar width), this is due to the panel content being placed
next to the sidebar, so therefore the content has to move 400
(PANEL_WIDTH) + 56 (sidebar_width) backwards, for the overlay to have a
width of 0 on hide.
I tried also updating the colours to the "new" versions from designs but
they don't match due to colour profile differences (so I'm not yet sure
if they are correct or not) and also don't look great without all the UI
elements also being updated.