Allow customizing the pane's following border width in the theme

crates/theme/src/theme.rs

@@ -36,6 +36,7 @@ pub struct Workspace {
     pub active_tab: Tab,
     pub pane_divider: Border,
     pub leader_border_opacity: f32,
+    pub leader_border_width: f32,
     pub left_sidebar: Sidebar,
     pub right_sidebar: Sidebar,
     pub status_bar: StatusBar,

crates/workspace/src/pane_group.rs

@@ -111,7 +111,7 @@ impl Member {
                         .editor
                         .replica_selection_style(leader.replica_id)
                         .cursor;
-                    border = Border::all(1.0, leader_color);
+                    border = Border::all(theme.workspace.leader_border_width, leader_color);
                     border
                         .color
                         .fade_out(1. - theme.workspace.leader_border_opacity);

crates/zed/assets/themes/_base.toml

@@ -4,7 +4,8 @@ base = { family = "Zed Sans", size = 14 }
 [workspace]
 background = "$surface.0"
 pane_divider = { width = 1, color = "$border.0" }
-leader_border_opacity = 0.6
+leader_border_opacity = 0.7
+leader_border_width = 2.0
 
 [workspace.titlebar]
 height = 32