- removed js margin-top/-bottom generation
- added layout-navbar-not-fixed & layout-footer-not-fixed incl. responsive variants (eg. layout-*-navbar-not-fixed, layout-*-footer-not-fixed)
- added responsive variants for fixed (eg. layout-*-navbar-fixed, layout-*-footer-fixed)
- added default border-bottom to main-header navbar like main-footer
- removed .border-bottom from main-header navbar in demo pages