Tab bar outline improvements

Closes #717

CHANGELOG.md

@@ -22,8 +22,9 @@ Release date: TBD
 [#746](https://github.com/mattermost/desktop/pull/746)
 - Hide hovering URL bar for internal links.
 [#745](https://github.com/mattermost/desktop/pull/745)
-- Truncate long server names in server tabs.
+- Improved appearance of server tabs.
 [#518](https://github.com/mattermost/desktop/issues/518)
+[#717](https://github.com/mattermost/desktop/issues/717)
 - Updated Mattermost animation icon which is displayed when loading a page.
 [#748](https://github.com/mattermost/desktop/issues/748)
 
@@ -54,6 +55,8 @@ Release date: TBD
 [#579](https://github.com/mattermost/desktop/issues/579)
 - Fixed an issue where Windows installer crashed in some cases.
 [#728](https://github.com/mattermost/desktop/issues/728)
+- Fixed outline on tab bar disappearing on hover.
+[#717](https://github.com/mattermost/desktop/issues/717)
 
 #### Mac
 - Fixed an issue where app crashed after toggling "Show Mattermost icon in menu bar" setting.

src/browser/css/components/TabBar.css

@@ -18,6 +18,12 @@
   padding: 0 15px;
 }
 
+.TabBar>li.teamTabItem:not(.active)>a:hover {
+  background-color: #e6e6e6;
+  border: 1px solid #ddd;
+  transition: background-color 0.2s ease;
+}
+
 .TabBar .TabBar-addServerButton>a {
   border: none;
   background: transparent;
@@ -30,6 +36,7 @@
   color: #333;
   background-color: #e6e6e6;
   border-color: #adadad;
+  transition: background-color 0.2s ease;
 }
 
 .TabBar .TabBar-badge {