Chore: Updated mat inputs to better match the style guide. Removed placeholders in favour of labels.

overlord/src/app/period/period-detail/period-detail.component.html

@@ -6,10 +6,10 @@
     <form [formGroup]="form" class="flex flex-col">
       <div class="flex flex-row justify-around content-start items-start">
         <mat-form-field class="flex-auto">
+          <mat-label>Valid From</mat-label>
           <input
             matInput
             [matDatepicker]="validFrom"
-            placeholder="Valid From"
             formControlName="validFrom"
             autocomplete="off"
           />
@@ -19,10 +19,10 @@
       </div>
       <div class="flex flex-row justify-around content-start items-start">
         <mat-form-field class="flex-auto">
+          <mat-label>Valid Till</mat-label>
           <input
             matInput
             [matDatepicker]="validTill"
-            placeholder="Valid Till"
             formControlName="validTill"
             autocomplete="off"
           />