apply type colors to placeholders

frontend/src/app/components/wp-table/timeline/cells/timeline-cell-renderer.ts

@@ -79,13 +79,14 @@ export class TimelineCellRenderer {
 
     const placeholder = document.createElement('div');
     placeholder.style.pointerEvents = 'none';
-    placeholder.style.backgroundColor = '#DDDDDD';
     placeholder.style.position = 'absolute';
     placeholder.style.height = '1em';
     placeholder.style.width = '30px';
     placeholder.style.zIndex = '9999';
     placeholder.style.left = (days * renderInfo.viewParams.pixelPerDay) + 'px';
 
+    this.applyTypeColor(renderInfo, placeholder);
+
     return placeholder;
   }
 

frontend/src/app/components/wp-table/timeline/cells/timeline-milestone-cell-renderer.ts

@@ -52,6 +52,8 @@ export class TimelineMilestoneCellRenderer extends TimelineCellRenderer {
     diamond.style.width = '1em';
     placeholder.appendChild(diamond);
 
+    this.applyTypeColor(renderInfo, diamond);
+
     return placeholder;
   }