New nested param table styles for REST (#30862)

components/parameter-table/ParameterTable.module.scss

@@ -0,0 +1,20 @@
+.parameterTable {
+  // this is for the child parameter table row that contiains the top level
+  // properties details toggle element because we want it to match the
+  // background color of the top level parameter rows.  We need the !important
+  // because the child parameter rows (the nested expanded properties) otherwise
+  // have the same background color.
+  & > tbody > tr {
+    background: var(--color-canvas-default) !important;
+  }
+
+  // also for the top level child parameter table row, we want the details toggle
+  // to align with the top level parameter rows.  Child parameter rows have some
+  // left padding so they can indent as they nest but we don't want that in
+  // this case.  We need the !important to override general default markdown
+  // article styling.
+  & > tbody > tr > td > details {
+    padding-left: 0px !important;
+    margin-bottom: 4px !important;
+  }
+}