Improve 'strong' text style to be less bold and have letter spacing

This improves bold text readability.
This has to be done in the actual element, in the TextEditor and on the 
properties panel.

projects/common/element-components/text.component.ts

@@ -28,21 +28,22 @@ import { TextElement } from '../models/text-element';
           <mat-icon>clear</mat-icon>
         </button>
       </div>
-      <div [style.background-color]="elementModel.backgroundColor"
+      <div #container class="text-container"
+           [style.background-color]="elementModel.backgroundColor"
            [style.color]="elementModel.fontColor"
            [style.font-family]="elementModel.font"
            [style.line-height.%]="elementModel.lineHeight"
            [style.font-weight]="elementModel.bold ? 'bold' : ''"
            [style.font-style]="elementModel.italic ? 'italic' : ''"
            [style.text-decoration]="elementModel.underline ? 'underline' : ''"
-           [innerHTML]="elementModel.text | safeResourceHTML"
-           #container>
+           [innerHTML]="elementModel.text | safeResourceHTML">
       </div>
     </div>
   `,
   styles: [
     '.marking-bar{position: sticky; top: 0; margin-bottom: 15px}',
-    '.marking-button{color: #333}'
+    '.marking-button{color: #333}',
+    '::ng-deep .text-container p strong {letter-spacing: 0.04em; font-weight: 600}'
   ]
 })
 export class TextComponent extends ElementComponent {

projects/editor/src/app/text-editor/rich-text-editor.component.css

@@ -27,3 +27,8 @@ app-rich-text-editor .editor-control-line {
   height: 50px;
   margin-bottom: 5px;
 }
+
+.ProseMirror p strong {
+  letter-spacing: 0.04em !important;
+  font-weight: 600 !important;
+}

projects/editor/src/app/unit-view/page-view/properties-panel/element-properties.component.css

@@ -37,3 +37,8 @@ mat-divider {
   border-top-width: 9px;
   border-top-style: dotted;
 }
+
+::ng-deep app-element-properties p strong {
+  letter-spacing: 0.04em !important;
+  font-weight: 600 !important;
+}