MDL-63378 theme_boost: Contrast of menu items

Enforce the :active menu text colour during a mouse click on an action menu.

theme/boost/scss/moodle/core.scss

@@ -2047,6 +2047,9 @@ $footer-link-color: $bg-inverse-link-color !default;
     width: 100%;
     color: $body-color;
 }
+.dropdown-item:active a {
+    color: $dropdown-link-active-color;
+}
 
 .competency-tree {
     ul {

theme/boost/style/moodle.css

@@ -10374,6 +10374,9 @@ ul {
   width: 100%;
   color: #373a3c; }
 
+.dropdown-item:active a {
+  color: #fff; }
+
 .competency-tree ul {
   padding-left: 1.5rem; }