fix background color for details page history tooltip.

fixes #283

webapp/frontend/src/styles/styles.scss

@@ -5,14 +5,20 @@
 //  modifications of third party libraries.
 // -----------------------------------------------------------------------------------------------------
 
-.treo-theme-dark .yellow-50 {
+.treo-theme-dark {
-    background-color: #242b38 !important;
+    .yellow-50 {
+        background-color: #242b38 !important;
 
-    .mat-icon {
+        .mat-icon {
-        color: #0694a2 !important;
+            color: #0694a2 !important;
-    }
+        }
 
-    .text-secondary {
+        .text-secondary {
-        color: #0694a2 !important
+            color: #0694a2 !important
+        }
+    }
+    .apexcharts-tooltip {
+        background: #242b38 !important;
+        //color: orange;
     }
 }