refactor: address loading review findings (#18)

frontend/src/styles.scss

@@ -144,6 +144,30 @@ p {
   min-height: 220px;
 }
 
+.visually-hidden {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}
+
+.busy-fieldset {
+  min-width: 0;
+  margin: 0;
+  padding: 0;
+  border: 0;
+}
+
+.primary-action mat-spinner {
+  display: inline-block;
+  margin-right: 8px;
+  vertical-align: middle;
+}
+
 .load-error,
 .refresh-error {
   padding: 20px;