Put back stupid horrible overflow:auto to keep sidebars from

shoving down all content

Was removed from most boxes in 30ddb35f0; put it back here only
on mid- and full- content. No need for it on small.
Apparently I suck at reviewing shit.

Bug: T181323
Change-Id: Ic0bc08b9ba542ac16936c27e1dcdaca140fd51a2

resources/screen-desktop-full.less

@@ -7,6 +7,7 @@
 #mw-content {
 	margin-left: @column-left-size;
 	margin-right: @column-right-size;
+	overflow: auto;
 }
 
 #mw-related-navigation {

resources/screen-desktop-mid.less

@@ -11,6 +11,7 @@
 
 #mw-content {
 	margin-left: @column-left-size;
+	overflow: auto;
 }
 
 // Redundant content category list