Appearance of the bottom bars.
If set to [enum@Adw.ToolbarStyle.flat], bottom bars are flat and scrolling content has a subtle undershoot shadow when touching them, same as the [`.undershoot-bottom`](style-classes.html#undershoot-indicators) style class. This works well for simple content, e.g. [ class@StatusPage] or [class@PreferencesPage], where the background at the bottom of the page is uniform. Additionally, windows with sidebars should always use this style.
Undershoot shadow is only present if a bottom bar is actually present and visible. It is also never present if [ property@ToolbarView:extend-content-to-bottom-edge] is set to `TRUE`.
If set to [enum@Adw.ToolbarStyle.raised], bottom bars have an opaque background and a persistent shadow, this is suitable for content such as utility panes, where some elements are directly adjacent to the bottom bars, or [class@TabView], where each page can have a different background.
[enum@Adw.ToolbarStyle.raised-border] is similar to [enum@Adw.ToolbarStyle.raised], but the shadow is replaced with a more subtle border. This can be useful for applications like image viewers.
See also [property@ToolbarView:top-bar-style].