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/install.tmpl

@@ -19,7 +19,7 @@
 						<div class="ui selection database type dropdown">
 							<input type="hidden" id="db_type" name="db_type" value="{{.CurDbOption}}">
 							<div class="text">{{.CurDbOption}}</div>
-							<i class="dropdown icon"></i>
+							{{svg "octicon-triangle-down" 14 "dropdown icon"}}
 							<div class="menu">
 								{{range .DbOptions}}
 									<div class="item" data-value="{{.}}">{{.}}</div>
@@ -54,7 +54,7 @@
 							<div class="ui selection database type dropdown">
 								<input type="hidden" name="ssl_mode" value="{{if .ssl_mode}}{{.ssl_mode}}{{else}}disable{{end}}">
 								<div class="default text">disable</div>
-								<i class="dropdown icon"></i>
+								{{svg "octicon-triangle-down" 14 "dropdown icon"}}
 								<div class="menu">
 									<div class="item" data-value="disable">Disable</div>
 									<div class="item" data-value="require">Require</div>
@@ -75,7 +75,7 @@
 							<div class="ui selection database type dropdown">
 								<input type="hidden" name="charset" value="{{if .charset}}{{.charset}}{{else}}utf8mb4{{end}}">
 								<div class="default text">utf8mb4</div>
-								<i class="dropdown icon"></i>
+								{{svg "octicon-triangle-down" 14 "dropdown icon"}}
 								<div class="menu">
 									<div class="item" data-value="utf8mb4">utf8mb4</div>
 									<div class="item" data-value="utf8">utf8</div>