Fix dropdown submenu arrow invisible in non-hovered state (#44)

* Fix dropdown submenu arrow invisible in non-hovered state (#3909)

The dropdown-submenu arrow was using --bs-dropdown-link-active-color
(#fff) which is invisible against the white background. Change to
--bs-dropdown-link-color (#ccc) to make the arrow visible, matching
the behavior from MkDocs 1.5.2 and earlier.

Closes mkdocs/mkdocs#3909

* Add release note for dropdown submenu arrow fix (#3909)

* Apply suggestion from @shenxianpeng

Author: shenxianpeng

docs/about/release-notes.md

@@ -27,8 +27,9 @@ The current members of the MkDocs-NG team.
 
 ### Fixed
 
-* Fix build crash caused by broken (dangling) symlinks in the docs directory. #46
+* Fix dropdown submenu arrow invisible in the navigation menu. #44
 * Fix malformed URLs (e.g., unterminated IPv6 literals) crashing the entire build. #45
+* Fix build crash caused by broken (dangling) symlinks in the docs directory. #46
 
 ## Version 1.7.1 (2026-04-25)
 

mkdocs/themes/mkdocs/css/base.css

@@ -323,7 +323,7 @@ details h4, details h5, details h6 {
     border-color: transparent;
     border-style: solid;
     border-width: 5px 0 5px 5px;
-    border-left-color: var(--bs-dropdown-link-active-color);
+    border-left-color: var(--bs-dropdown-link-color);
     margin-top: 5px;
     margin-right: -10px;
 }