Fix default theme-auto selector when nologin (#21346)

rock2dust · silverwind · zeripath · web-flow · commit 1294f6c511d0 · 2022-10-06T11:52:43.000+08:00
the bug is theme selector is `theme-` when not login to Gitea ![theme-auto](https://user-images.githubusercontent.com/76462613/194099390-0ff6854a-1eb9-4dba-bb28-fd238f2225f8.png) Co-authored-by: silverwind <me@silverwind.io> Co-authored-by: zeripath <art27@cantab.net> Co-authored-by: delvh <dev.lh@web.de> Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
diff --git a/templates/base/head.tmpl b/templates/base/head.tmpl
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html lang="{{.locale.Lang}}" class="theme-{{.SignedUser.Theme}}">
+<html lang="{{.locale.Lang}}" class="theme-{{if .SignedUser.Theme}}{{.SignedUser.Theme}}{{else}}auto{{end}}">
 <head>
 	<meta charset="utf-8">
 	<meta name="viewport" content="width=device-width, initial-scale=1">
