Fix border color of drop area in import activities dialog (dark mode)

apps/client/src/app/pages/portfolio/activities/import-activities-dialog/import-activities-dialog.scss

@@ -82,10 +82,12 @@
 }
 
 :host-context(.theme-dark) {
+  .mat-mdc-dialog-content {
     .drop-area {
       border-color: rgba(
         var(--palette-foreground-divider-dark),
-      var(--palette-foreground-divider-alpha-dark)
+        var(--palette-foreground-divider-dark-alpha)
       );
     }
+  }
 }