Fix text element with background color and text color at the same time

Highlighted (background colored) text is done with mark elements which
don't have a color and make the contained text lose the styling of the
parent span, which has the text-color property.
To solve it we simply inherit the color of the parent span.

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

@@ -67,7 +67,8 @@ import { ValueChangeElement } from '../models/uI-element';
     '::ng-deep .text-container h1 {font-weight: bold; font-size: 20px;}',
     '::ng-deep .text-container h2 {font-weight: bold; font-size: 18px;}',
     '::ng-deep .text-container h3 {font-weight: bold; font-size: 16px;}',
-    '::ng-deep .text-container h4 {font-weight: normal; font-size: 16px;}'
+    '::ng-deep .text-container h4 {font-weight: normal; font-size: 16px;}',
+    'mark {color: inherit}'
   ]
 })
 export class TextComponent extends ElementComponent {

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

@@ -53,3 +53,7 @@
   font-weight: normal;
   font-size: 16px;
 }
+
+mark {
+  color: inherit;
+}

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

@@ -87,3 +87,7 @@ app-rich-text-editor .editor-controls-second-line {
 .special-chars-button {
   margin-left: 25px;
 }
+
+mark {
+  color: inherit;
+}