Multi diff editor: remove left/right margins (fix microsoft#204891) (microsoft#210381)

Author: bpasero

src/vs/editor/browser/widget/multiDiffEditor/style.css

@@ -36,14 +36,10 @@
 			}
 
 			.header-content {
-				margin: 8px 8px 0px 8px;
+				margin: 8px 0px 0px 0px;
 				padding: 4px 5px;
 
 				border-top: 1px solid var(--vscode-multiDiffEditor-border);
-				border-right: 1px solid var(--vscode-multiDiffEditor-border);
-				border-left: 1px solid var(--vscode-multiDiffEditor-border);
-				border-top-left-radius: 2px;
-				border-top-right-radius: 2px;
 
 				display: flex;
 				align-items: center;
@@ -107,13 +103,7 @@
 			display: flex;
 			flex-direction: column;
 
-			margin-right: 8px;
-			margin-left: 8px;
-
-			border-right: 1px solid var(--vscode-multiDiffEditor-border);
-			border-left: 1px solid var(--vscode-multiDiffEditor-border);
 			border-bottom: 1px solid var(--vscode-multiDiffEditor-border);
-			border-radius: 2px;
 			overflow: hidden;
 		}