Comment box tweaks and SVG dropdown triangles (#13376)

* Comment box tweaks and SVG dropdown triangles

- Change all dropdown triangles to SVG
- Bring inline review comment box closer to regular comment boxes
- Enhance arc-green checkbox contrast
- Minor reaction tweaks
- Flexbox the diff file header

* remove a border

* fix type marker in arc-green

* add small code padding

* fix position regression and remove useless rules

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

templates/repo/release/list.tmpl

@@ -82,7 +82,7 @@
 							<div class="download">
 								<div class="ui accordion">
 									<h2 class="title {{if eq $idx 0}}active{{end}}">
-										<i class="dropdown icon"></i>
+										{{svg "octicon-triangle-down" 14 "dropdown icon"}}
 										{{$.i18n.Tr "repo.release.downloads"}}
 									</h2>
 									<div class="content {{if eq $idx 0}}active{{end}}">

templates/repo/release/new.tmpl

@@ -28,7 +28,7 @@
 								{{.i18n.Tr "repo.release.target"}} :
 								<strong id="repo-branch-current">{{.Repository.DefaultBranch}}</strong>
 							</div>
-							<i class="dropdown icon"></i>
+							{{svg "octicon-triangle-down" 14 "dropdown icon"}}
 							<div class="menu">
 								{{range .Branches}}
 									<div class="item" data-value="{{.}}">{{.}}</div>