Fix assignee list overlapping in Issue sidebar (go-gitea#33176)

Fix  go-gitea#33170

![image](https://github.com/user-attachments/assets/714cebdc-ee76-43e3-9ece-a189f8ecb17a)

![image](https://github.com/user-attachments/assets/cbb58425-42b4-41ee-ba3c-7efbd24607dc)

Author: wxiaoguang

templates/repo/issue/sidebar/assignee_list.tmpl

@@ -16,20 +16,20 @@
 				<input type="text" placeholder="{{ctx.Locale.Tr "repo.issues.filter_assignees"}}">
 			</div>
 			<div class="item clear-selection">{{ctx.Locale.Tr "repo.issues.new.clear_assignees"}}</div>
-			<div class="scrolling menu">
+			<div class="scrolling menu flex-items-block">
 				{{range $data.CandidateAssignees}}
-					<a class="item muted" href="#" data-value="{{.ID}}">
+					<a class="item" href="#" data-value="{{.ID}}">
 						<span class="item-check-mark">{{svg "octicon-check"}}</span>
 						{{ctx.AvatarUtils.Avatar . 20}} {{template "repo/search_name" .}}
 					</a>
 				{{end}}
 			</div>
 		</div>
 	</div>
-	<div class="ui list tw-flex tw-flex-row tw-gap-2">
+	<div class="ui list muted-links flex-items-block tw-flex tw-flex-col tw-gap-2">
 		<span class="item empty-list {{if $issueAssignees}}tw-hidden{{end}}">{{ctx.Locale.Tr "repo.issues.new.no_assignees"}}</span>
 		{{range $issueAssignees}}
-			<a class="item muted" href="{{$pageMeta.RepoLink}}/{{if $pageMeta.IsPullRequest}}pulls{{else}}issues{{end}}?assignee={{.ID}}">
+			<a class="item" href="{{$pageMeta.RepoLink}}/{{if $pageMeta.IsPullRequest}}pulls{{else}}issues{{end}}?assignee={{.ID}}">
 					{{ctx.AvatarUtils.Avatar . 20}} {{.GetDisplayName}}
 			</a>
 		{{end}}