diff --git a/resources/skins.vector.styles/Sidebar.less b/resources/skins.vector.styles/Sidebar.less
index f7516576..859154f5 100644
--- a/resources/skins.vector.styles/Sidebar.less
+++ b/resources/skins.vector.styles/Sidebar.less
@@ -21,9 +21,9 @@
 	.mw-checkbox-hack-button {
 		// The icon is only 44px tall but the header is 50px. Offset by the difference from the logo
 		// icon and center with respect to the header.
-		top: @height-logo-icon - @size-sidebar-button + ( @height-header - @height-logo-icon ) / 2;
-		// Some made up value to be revised by Alex.
-		left: 10px;
+		top: @margin-top-header + ( ( @height-logo-icon - @size-sidebar-button ) / 2 );
+		// FIXME: Replace by proper calculation and variable.
+		left: 14px;
 	}
 
 	.mw-checkbox-hack-button {
diff --git a/variables.less b/variables.less
index 5b82fa5e..92a11842 100644
--- a/variables.less
+++ b/variables.less
@@ -61,6 +61,7 @@
 @line-height-footer-info: 1.4;
 @line-height-footer-buttons: 2;
 
+@size-sidebar-button: unit( 44 / @font-size-browser, em ); // Equals `2.75em`.
 // FIXME: Use global variable since Echo and CentralNotice use this variable
 @border-color-content: #a7d7f9;
 // Due to darker background gradient, border needs to be darkened for aligned visual perception.
@@ -138,5 +139,3 @@
 
 // Transitions
 @transition-duration-base: 100ms;
-
-@size-sidebar-button: 2.75em; // 44px