Angular Material In Depth

Author: Your Name

src/app/course/course.component.html

@@ -54,7 +54,10 @@ <h2>{{course?.description}}</h2>
 
         </tr>
 
-        <tr mat-row *matRowDef="let lesson;columns:['expandedDetail']"></tr>
+        <tr mat-row *matRowDef="let lesson;columns:['expandedDetail']"
+            [class.collapsed-detail]="lesson != expandedLesson">
+
+        </tr>
 
 
     </table>

src/app/course/course.component.scss

@@ -16,6 +16,10 @@
     margin: 10px auto;
 }
 
+.collapsed-detail {
+  display: none;
+}
+
 .duration-cell {
     text-align: center;
 }