Add responsive open / close logic. Remove open and close button.

src/app/degree-planner/degree-planner.component.html

@@ -35,7 +35,8 @@
         cdkFocusRegionEnd
         (closedStart)="closeSidenav()"
         [mode]="mobileView.matches ? 'over' : 'side'"
-        [opened]="isSidenavOpen$ | async">
+        [disableClose]="!mobileView.matches"
+        [opened]="(isSidenavOpen$ | async) || !mobileView.matches">
         <cse-sidenav-menu-item></cse-sidenav-menu-item>
       </mat-sidenav>
 
@@ -129,39 +130,6 @@
               Add degree plan
             </button>
           </mat-menu>
-
-          <button
-            *ngIf="isSidenavOpen$ | async; else closeButton"
-            (click)="closeSidenav()"
-            id="menu-toggle-btn"
-            mat-button
-            fxHide.lt-md="true"
-            aria-label="Close sidenav menu">
-            <i
-              class="material-icons"
-              alt="Close sidenav"
-              matTooltip="Close sidenav menu"
-              matTooltipPosition="above">
-              chevron_right
-            </i>
-          </button>
-
-          <ng-template #closeButton>
-            <button
-              (click)="openSidenav()"
-              id="menu-toggle-btn"
-              mat-button
-              fxHide.lt-md="true"
-              aria-label="Open sidenav menu">
-              <i
-                class="material-icons"
-                alt="Open sidenav"
-                matTooltip="Open sidenav menu"
-                matTooltipPosition="above">
-                chevron_left
-              </i>
-            </button>
-          </ng-template>
         </div>
 
         <div