Add gitea-dark theme

.stylelintrc

@@ -5,6 +5,7 @@ rules:
   block-closing-brace-empty-line-before: null
   color-hex-length: null
   comment-empty-line-before: null
+  custom-property-empty-line-before: null
   declaration-empty-line-before: null
   indentation: 4
   no-descending-specificity: null

custom/conf/app.example.ini

@@ -181,7 +181,7 @@ SHOW_USER_EMAIL = true
 ; Set the default theme for the Gitea install
 DEFAULT_THEME = gitea
 ; All available themes. Allow users select personalized themes regardless of the value of `DEFAULT_THEME`.
-THEMES = gitea,arc-green
+THEMES = gitea,gitea-dark,arc-green
 ;All available reactions users can choose on issues/prs and comments.
 ;Values can be emoji alias (:smile:) or a unicode emoji.
 ;For custom reactions, add a tightly cropped square image to public/emoji/img/reaction_name.png

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -129,8 +129,8 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
 - `FEED_MAX_COMMIT_NUM`: **5**: Number of maximum commits shown in one activity feed.
 - `FEED_PAGING_NUM`: **20**: Number of items that are displayed in home feed.
 - `GRAPH_MAX_COMMIT_NUM`: **100**: Number of maximum commits shown in the commit graph.
-- `DEFAULT_THEME`: **gitea**: \[gitea, arc-green\]: Set the default theme for the Gitea install.
-- `THEMES`:  **gitea,arc-green**: All available themes. Allow users select personalized themes
+- `DEFAULT_THEME`: **gitea**: \[gitea, gitea-dark, arc-green\]: Set the default theme for the Gitea install.
+- `THEMES`:  **gitea,gitea-dark,arc-green**: All available themes. Allow users select personalized themes
   regardless of the value of `DEFAULT_THEME`.
 - `REACTIONS`: All available reactions users can choose on issues/prs and comments
     Values can be emoji alias (:smile:) or a unicode emoji.

docs/content/doc/advanced/customizing-gitea.en-us.md

@@ -293,5 +293,5 @@ A full list of supported emoji's is at [emoji list](https://gitea.com/gitea/gite
 
 ## Customizing the look of Gitea
 
-As of version 1.6.0 Gitea has built-in themes. The two built-in themes are, the default theme `gitea`, and a dark theme `arc-green`. To change the look of your Gitea install change the value of `DEFAULT_THEME` in the [ui](https://docs.gitea.io/en-us/config-cheat-sheet/#ui-ui) section of `app.ini` to another one of the available options.  
-As of version 1.8.0 Gitea also has per-user themes. The list of themes a user can choose from can be configured with the `THEMES` value in the [ui](https://docs.gitea.io/en-us/config-cheat-sheet/#ui-ui) section of `app.ini` (defaults to `gitea` and `arc-green`, light and dark respectively)
+As of version 1.6.0 Gitea has built-in themes. The built-in themes are the light theme `gitea` and the dark themes `gitea-dark` and `arc-green`. To change the look of your Gitea install change the value of `DEFAULT_THEME` in the [ui](https://docs.gitea.io/en-us/config-cheat-sheet/#ui-ui) section of `app.ini` to another one of the available options.  
+As of version 1.8.0 Gitea also has per-user themes. The list of themes a user can choose from can be configured with the `THEMES` value in the [ui](https://docs.gitea.io/en-us/config-cheat-sheet/#ui-ui) section of `app.ini`.

modules/setting/setting.go

@@ -215,7 +215,7 @@ var (
 		ThemeColorMetaTag:   `#6cc644`,
 		MaxDisplayFileSize:  8388608,
 		DefaultTheme:        `gitea`,
-		Themes:              []string{`gitea`, `arc-green`},
+		Themes:              []string{`gitea`, `gitea-dark`, `arc-green`},
 		Reactions:           []string{`+1`, `-1`, `laugh`, `hooray`, `confused`, `heart`, `rocket`, `eyes`},
 		Notification: struct {
 			MinTimeout            time.Duration