[Glitch] Fix link colors in announcements

Port 3ae0b03603 to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/styles/components/announcements.scss

@@ -17,7 +17,7 @@
   }
 
   a {
-    color: $highlight-text-color;
+    color: $secondary-text-color;
     text-decoration: none;
 
     &:hover {
@@ -33,6 +33,10 @@
         }
       }
     }
+
+    &.unhandled-link {
+      color: lighten($ui-highlight-color, 8%);
+    }
   }
 }