fix component interaction with sub-components

pdb-js/src/app/limit-by/limit-by.component.html

@@ -1,4 +1,4 @@
-<mat-form-field id="limitBy">
+<mat-form-field class="pdb-form-mid">
   <mat-label>Limit By:</mat-label>
   <mat-select [(value)]="limitBy">
     <mat-option value="NO_LIMIT">no limit</mat-option>
@@ -9,14 +9,13 @@
   </mat-select>
 </mat-form-field>
 
-<mat-form-field id="limit"
+<mat-form-field class="pdb-form-number"
   *ngIf="limitBy !== 'NO_LIMIT'">
   <input 
     matInput 
     type="number" 
     placeholder="Limit" 
     min="1" 
-    value="{{limit}}"
-    
+    [(ngModel)]="limit"
     >
 </mat-form-field>