Various UI fixes (#25264)

Numerous small UI fixes:

- Fix double border in collaborator list
- Fix system notice table background
- Mute links in repo and org lists
- Downsize projects edit buttons
- Improve milestones and project list rendering
- Condense milestone list entry to a single line of "metas"
- Mute ".." button in repo files list

templates/repo/issue/milestone_issues.tmpl

@@ -33,10 +33,14 @@
 					{{if .IsClosed}}
 						{{svg "octicon-clock"}} {{$.locale.Tr "repo.milestones.closed" $closedDate | Safe}}
 					{{else}}
-						{{svg "octicon-calendar"}}
+
 						{{if .Milestone.DeadlineString}}
-							<span {{if .IsOverdue}}class="overdue"{{end}}>{{DateTime "short" .Milestone.DeadlineString}}</span>
+							<span{{if .IsOverdue}} class="text red"{{end}}>
+								{{svg "octicon-calendar"}}
+								{{DateTime "short" .Milestone.DeadlineString}}
+							</span>
 						{{else}}
+							{{svg "octicon-calendar"}}
 							{{$.locale.Tr "repo.milestones.no_due_date"}}
 						{{end}}
 					{{end}}

templates/repo/issue/milestones.tmpl

@@ -94,12 +94,13 @@
 									{{svg "octicon-clock" 14}}
 									{{$.locale.Tr "repo.milestones.closed" $closedDate | Safe}}
 								{{else}}
-									{{svg "octicon-calendar" 14}}
 									{{if .DeadlineString}}
-										<span {{if .IsOverdue}}class="overdue"{{end}}>
+										<span{{if .IsOverdue}} class="text red"{{end}}>
+											{{svg "octicon-calendar" 14}}
 											{{DateTime "short" .DeadlineString}}
 										</span>
 									{{else}}
+										{{svg "octicon-calendar" 14}}
 										{{$.locale.Tr "repo.milestones.no_due_date"}}
 									{{end}}
 								{{end}}

templates/repo/projects/view.tmpl

@@ -49,7 +49,7 @@
 			</div>
 			{{if and $.CanWriteProjects (not $.Repository.IsArchived)}}
 				<div class="column right aligned">
-					<div class="ui compact right small menu">
+					<div class="ui compact right mini menu">
 						<a class="item" href="{{$.RepoLink}}/projects/{{.Project.ID}}/edit?redirect=project">
 							{{svg "octicon-pencil"}}
 							<span class="gt-mx-3">{{$.locale.Tr "repo.issues.label_edit"}}</span>

templates/repo/view_list.tmpl

@@ -40,7 +40,7 @@
 	<tbody>
 		{{if .HasParentPath}}
 			<tr class="has-parent">
-				<td colspan="3">{{svg "octicon-reply"}}<a href="{{.BranchLink}}{{if .ParentPath}}{{PathEscapeSegments .ParentPath}}{{end}}">..</a></td>
+				<td colspan="3">{{svg "octicon-reply"}}<a class="muted" href="{{.BranchLink}}{{if .ParentPath}}{{PathEscapeSegments .ParentPath}}{{end}}">..</a></td>
 			</tr>
 		{{end}}
 		{{range $item := .Files}}