Zibll dual-column relies on margin carving out .content-layout while width
stays auto. Under border-box, width:100% + margin-right kept the border-box
at full container width so .sidebar (margin-left:-311px) sat under the main
column. Drop the forced 100% width, pin layout 2/3 gutters and sidebar
negative margins to Zibll's 311px (+ CSS var fallback).
kate522
6ce6ce44e4