DevTools: [SSP] fix "insert style rule" button on mac

Source/devtools/front_end/sidebarPane.css

Index: Source/devtools/front_end/sidebarPane.css
diff --git a/Source/devtools/front_end/sidebarPane.css b/Source/devtools/front_end/sidebarPane.css
index 622b354759bd57f17fb3bbfd7d447c8fc88ce823..2bf20aec315dd8e0abbb51ef174d56e5f3acbe73 100644
--- a/Source/devtools/front_end/sidebarPane.css
+++ b/Source/devtools/front_end/sidebarPane.css
@@ -200,8 +200,8 @@
     background-position: 0 0;
     position: absolute;
     height: 16px;
-    width: 22px;
-    right: 0px;
+    width: 23px;
+    right: 10px;
     bottom: 1px;
     visibility: hidden;
 }
@@ -212,4 +212,4 @@
 
 .sidebar-pane-button-new-rule:hover {
     background-position: -23px 0;
-}
+}