diff --git a/packages/core/src/browser/style/dockpanel.css b/packages/core/src/browser/style/dockpanel.css
index 8f6a8636d87f3..e55e30e435339 100644
--- a/packages/core/src/browser/style/dockpanel.css
+++ b/packages/core/src/browser/style/dockpanel.css
@@ -37,6 +37,11 @@
   border-left: var(--theia-border-width) solid var(--theia-border-color1);
 }
 
+.p-DockPanel-handle[data-orientation='horizontal']:after {
+  background-color: var(--theia-layout-color0);
+  border-left: var(--theia-border-width) solid var(--theia-border-color1);
+}
+
 .p-DockPanel-overlay {
   background: rgba(33, 150, 243, 0.1);
   border: var(--theia-border-width) dashed var(--theia-brand-color1);
diff --git a/packages/core/src/browser/style/tabs.css b/packages/core/src/browser/style/tabs.css
index d1fa09faeae91..a5507233e19e5 100644
--- a/packages/core/src/browser/style/tabs.css
+++ b/packages/core/src/browser/style/tabs.css
@@ -75,6 +75,10 @@
 | Tabs in the center area (main and bottom)
 |----------------------------------------------------------------------------*/
 
+#theia-main-content-panel .p-Widget.p-DockPanel-widget {
+  background-color: var(--theia-layout-color0);
+}
+
 /* This is a current tab of a tab bar: each tab bar has 1. */
 .p-TabBar .p-TabBar-tab.p-mod-current {
   min-height: calc(var(--theia-private-horizontal-tab-height) + var(--theia-border-width));