Design header search bar.

frontend/src/app/components/header/header.component.html

@@ -8,10 +8,12 @@
     </a>
 </div>
 <div>
-    <input name="search-query" placeholder="Search something..." />
-    <button type="button">
-        <mat-icon>search</mat-icon>
-    </button>
+    <div class="search-bar">
+        <input name="search-query" placeholder="Search something..." />
+        <button type="button">
+            <mat-icon>search</mat-icon>
+        </button>
+    </div>
 </div>
 <div>
     <ng-container *ngIf="isAuthenticated; else anonymousRightMenu">