Made the theme picker sort from dark to light

Added a layer into 'ConstrainedBox' to clip it
's children

Made the welcome experience responsive to small and large sizes

crates/theme_selector/src/theme_selector.rs

@@ -50,7 +50,6 @@ impl ThemeSelector {
         theme_names.sort_unstable_by(|a, b| {
             a.is_light
                 .cmp(&b.is_light)
-                .reverse()
                 .then(a.name.cmp(&b.name))
         });
         let matches = theme_names