[player] Rework the appearance of `sections`

* Use all style attributes of the unit definition to display
sections
* Remove unnecessary div tag from `SectionComponent`

projects/player/src/app/page.component.ts

@@ -7,10 +7,11 @@ import { UnitPage } from '../../../common/unit';
     <app-section *ngFor="let section of page.sections; let i = index"
          [section]="section"
          [ngStyle]="{
-                width: '100%',
                 position: 'relative',
                 display: 'inline-block',
-                'height.px': section.height }">
+                'background-color': section.backgroundColor,
+                'height.px': section.height,
+                'width.px': section.width }">
       {{section.height}}
     </app-section>
   `

projects/player/src/app/section.component.ts

@@ -7,13 +7,8 @@ import * as ComponentUtils from '../../../common/component-utils';
 @Component({
   selector: 'app-section',
   template: `
-    <div fxLayout="column">
-        <ng-template #elementContainer></ng-template>
-    </div>
-    `,
-  styles: [
-    'div {position: absolute}'
-  ]
+    <ng-template #elementContainer></ng-template>
+  `
 })
 export class SectionComponent implements OnInit {
   @Input() section!: UnitPageSection;