feat: grey header when clicked

Author: Cooper

frontend/src/components/schedule6/index.scss

@@ -114,8 +114,12 @@
   margin: 0;
 }
 
-.schedule-6__totals-label {
-  font-weight: 600;
+// An expanded row keeps the grey its header shows on hover. `--cds-layer-hover` is the very token
+// Carbon's own `.cds--accordion__heading:hover` uses, so the two states match exactly and both
+// follow the active theme. Scoped to this page's accordion, and at three classes it outranks
+// Carbon's two-class hover rule.
+.schedule-6__section .cds--accordion__item--active > .cds--accordion__heading {
+  background-color: var(--cds-layer-hover);
 }
 
 .schedule-6__empty {

frontend/src/components/schedule6/index.tsx

@@ -788,7 +788,7 @@ const Schedule6: FC = () => {
 
         <Column sm={4} md={8} lg={16} className="schedule-6__section">
           <section aria-label="Totals" className="schedule-6__totals">
-            <span className="schedule-6__totals-label">Totals: </span>
+            <span>Totals: </span>
             {/* Its own container, NOT the record-row grid: that grid's 10rem minimum track is sized
                 for rows of inputs and wraps these three short numbers into a stack. */}
             <dl className="schedule-6__totals-fields">