theme: Fix entry could appear transparent on hover with certain themes (#40944)

Smit Barmase created 

Follow-up: https://github.com/zed-industries/zed/pull/34655  

We should use an opaque fallback color for `panel.overlay_hover`. This
helps when a custom theme doesn’t provide it, nor `element.hover`. For
example, VSCode’s default modern dark theme doesn’t include an
`element.hover` color after import.

Release Notes:

- Fixed an issue where the project panel’s sticky entry could appear
transparent on hover with certain themes.

Change summary

crates/theme/src/default_colors.rs | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Detailed changes

crates/theme/src/default_colors.rs 🔗 

@@ -85,7 +85,7 @@ impl ThemeColors {
             panel_indent_guide_hover: neutral().light_alpha().step_6(),
             panel_indent_guide_active: neutral().light_alpha().step_6(),
             panel_overlay_background: neutral().light().step_2(),
-            panel_overlay_hover: neutral().light_alpha().step_4(),
+            panel_overlay_hover: neutral().light().step_4(),
             pane_focused_border: blue().light().step_5(),
             pane_group_border: neutral().light().step_6(),
             scrollbar_thumb_background: neutral().light_alpha().step_3(),
@@ -220,7 +220,7 @@ impl ThemeColors {
             panel_indent_guide_hover: neutral().dark_alpha().step_6(),
             panel_indent_guide_active: neutral().dark_alpha().step_6(),
             panel_overlay_background: neutral().dark().step_2(),
-            panel_overlay_hover: neutral().dark_alpha().step_4(),
+            panel_overlay_hover: neutral().dark().step_4(),
             pane_focused_border: blue().dark().step_5(),
             pane_group_border: neutral().dark().step_6(),
             scrollbar_thumb_background: neutral().dark_alpha().step_3(),