Button and color enhancements (#24989) (#25176)

Backport #24989. Clean cherry-pick aside from one small conflict with
divider.

- Various corrections to button styles, especially secondary
- Remove focus highlight, it's annoying when it stays on button after
press
- Clearly define ghost and link buttons with demos in devtest
- Remove black, grey and tertiary buttons, they should not be used
- Make `arc-green` slightly darker

<img width="1226" alt="image"

src="https://github.com/go-gitea/gitea/assets/115237/8d89786a-01ab-40f8-ae5a-e17f40e35084">
<img width="1249" alt="image"

src="https://github.com/go-gitea/gitea/assets/115237/83651e6d-3c27-46ff-b8bd-ff344d70e949">

templates/repo/home.tmpl

@@ -30,7 +30,7 @@
 		</div>
 		<div class="gt-df gt-ac gt-fw gt-mt-3" id="repo-topics">
 			{{range .Topics}}<a class="ui repo-topic large label topic" href="{{AppSubUrl}}/explore/repos?q={{.Name}}&topic=1">{{.Name}}</a>{{end}}
-			{{if and .Permission.IsAdmin (not .Repository.IsArchived)}}<button id="manage_topic" class="ui tiny button button-ghost gt-ml-2">{{.locale.Tr "repo.topic.manage_topics"}}</button>{{end}}
+			{{if and .Permission.IsAdmin (not .Repository.IsArchived)}}<button id="manage_topic" class="btn interact-fg gt-ml-2 gt-font-12">{{.locale.Tr "repo.topic.manage_topics"}}</button>{{end}}
 		</div>
 		{{end}}
 		{{if and .Permission.IsAdmin (not .Repository.IsArchived)}}
@@ -46,7 +46,7 @@
 				</div>
 			</div>
 			<div>
-				<button class="ui basic button secondary" id="cancel_topic_edit">{{.locale.Tr "cancel"}}</button>
+				<button class="ui basic button" id="cancel_topic_edit">{{.locale.Tr "cancel"}}</button>
 				<button class="ui primary button" id="save_topic" data-link="{{.RepoLink}}/topics">{{.locale.Tr "save"}}</button>
 			</div>
 		</div>