fix microsoft#194193 (microsoft#194370)

Author: benibenj

src/vs/workbench/browser/parts/editor/media/multieditortabscontrol.css

@@ -242,7 +242,8 @@
 }
 
 .monaco-workbench .part.editor > .content .editor-group-container > .title .tabs-container > .tab.active.tab-border-top > .tab-border-top-container,
-.monaco-workbench .part.editor > .content .editor-group-container > .title .tabs-container > .tab.active.tab-border-bottom > .tab-border-bottom-container,
+.monaco-workbench .part.editor > .content .editor-group-container > .title:not(.two-tab-bars) .tabs-container > .tab.active.tab-border-bottom > .tab-border-bottom-container,
+.monaco-workbench .part.editor > .content .editor-group-container > .title.two-tab-bars .tabs-and-actions-container:not(:first-child)  .tabs-container > .tab.active.tab-border-bottom > .tab-border-bottom-container,
 .monaco-workbench .part.editor > .content .editor-group-container > .title .tabs-container > .tab.dirty-border-top > .tab-border-top-container {
 	display: block;
 	position: absolute;