Fix label color, fix divider in dropdown (#24215) (#24244)

Backport #24215 by @silverwind

Two small CSS fixes:

1. Fix basic primary label hover:

Before:
<img width="172" alt="Screenshot 2023-04-19 at 20 00 32"
src="https://user-images.githubusercontent.com/115237/233161903-eec2de54-1a58-44ac-a6ef-2d77157317f6.png">

After:
<img width="179" alt="Screenshot 2023-04-19 at 20 05 29"
src="https://user-images.githubusercontent.com/115237/233162028-995404ac-5852-4d03-821f-6eb4a918a9e3.png">

2. Fix border color of divider in dropdown and remove margin so it looks
better with hover effect, as discussed in
https://github.com/go-gitea/gitea/pull/24143:

<img width="205" alt="Screenshot 2023-04-19 at 20 03 24"
src="https://user-images.githubusercontent.com/115237/233162102-3f4a4142-9634-4c95-acf0-be57072ce7eb.png">
<img width="311" alt="Screenshot 2023-04-19 at 20 03 55"
src="https://user-images.githubusercontent.com/115237/233162109-faa616f6-02e4-43d3-95fa-66787a7f914c.png">

Co-authored-by: silverwind <me@silverwind.io>

web_src/css/base.css

@@ -2396,6 +2396,13 @@ a.ui.label:hover {
   color: var(--color-primary);
 }
 
+.ui.basic.labels a.primary.label:hover,
+a.ui.ui.ui.basic.primary.label:hover {
+  background: var(--color-hover);
+  border-color: var(--color-primary-dark-1);
+  color: var(--color-primary-dark-1);
+}
+
 .ui.basic.labels .secondary.label,
 .ui.ui.ui.basic.secondary.label {
   background: transparent;
@@ -2657,6 +2664,11 @@ table th[data-sortt-desc] .svg {
   border-radius: 0 0 var(--border-radius) var(--border-radius);
 }
 
+.ui.dropdown .menu > .divider {
+  border-top: 1px solid var(--color-secondary);
+  margin: 4px 0;
+}
+
 .ui.multiple.dropdown > .label {
   box-shadow: 0 0 0 1px var(--color-secondary) inset;
 }