refactor: legacyConfigForm UI (#130)

* refactor: update legacyConfigForm UI and divider colour

src/pages-and-resources/discussions/app-config-form/apps/legacy/LegacyConfigForm.jsx

@@ -71,15 +71,15 @@ function LegacyConfigForm({
               onChange={handleChange}
               values={values}
             />
-            <AppConfigFormDivider />
+            <AppConfigFormDivider thick />
+            <DiscussionTopics />
+            <AppConfigFormDivider thick />
             <DivisionByGroupFields
               onBlur={handleBlur}
               onChange={handleChange}
               appConfig={values}
             />
             <AppConfigFormDivider thick />
-            <DiscussionTopics />
-            <AppConfigFormDivider thick />
             <BlackoutDatesField
               errors={errors}
               onBlur={handleBlur}

src/pages-and-resources/discussions/app-config-form/apps/shared/AppConfigFormDivider.jsx

@@ -4,7 +4,7 @@ import PropTypes from 'prop-types';
 export default function AppConfigFormDivider({ thick }) {
   return (
     <hr
-      className="my-2 mx-sm-n5 mx-n4"
+      className="my-2 mx-sm-n5 mx-n4 border-light-300"
       style={{
         borderTopWidth: thick ? '3px' : '1px',
       }}

src/pages-and-resources/discussions/app-config-form/apps/shared/messages.js

@@ -18,12 +18,12 @@ const messages = defineMessages({
   },
   divideCourseTopicsByCohortsLabel: {
     id: 'authoring.discussions.builtIn.divideCourseTopicsByCohorts.label',
-    defaultMessage: 'Divide course wide discussion topics',
+    defaultMessage: 'Divide course-wide discussion topics',
     description: 'Label for a switch that enables dividing course wide topics by cohorts.',
   },
   divideCourseTopicsByCohortsHelp: {
     id: 'authoring.discussions.builtIn.divideCourseTopicsByCohorts.help',
-    defaultMessage: 'Choose which of your general course wide discussion topics you would like to divide.',
+    defaultMessage: 'Choose which of your general course-wide discussion topics you would like to divide.',
     description: 'Help text asking the user to pick course-wide topics that should be divided by cohort.',
   },
   divideGeneralTopic: {