Login and Registration: Correct focus color for links.

The hover color for links on the login screen was updated to use the admin color scheme CSS variables, but the focus color was left hardcoded. Update the focus color to use the same variable, so it matches hover and follows the selected admin color scheme.

Follow-up to [61681], [62113].

Props dhruvang21, hasnainashfaq, nimeshatxecurify, shailu25, softglaze, sumitsingh, vedantere, wildworks.
Fixes #64953.

git-svn-id: https://develop.svn.wordpress.org/trunk@62865 602fd350-edb4-49c9-b593-d223f7449a82

Author: t-hamano

src/wp-admin/css/login.css

@@ -32,7 +32,7 @@ a:active {
 }
 
 a:focus {
-	color: #043959;
+	color: var(--wp-admin-theme-color-darker-20);
 	box-shadow: 0 0 0 var(--wp-admin-border-width-focus, 1.5px) var(--wp-admin-theme-color, #3858e9);
 	/* Only visible in Windows High Contrast mode */
 	outline: 2px solid transparent;
@@ -339,7 +339,7 @@ p {
 .login #nav a:focus,
 .login #backtoblog a:focus,
 .login h1 a:focus {
-	color: #043959;
+	color: var(--wp-admin-theme-color-darker-20);
 }
 
 .login .privacy-policy-page-link {