changed heade size

-- xxlarge

Signed-off-by: shawnsandy <shawnsandy04@gmail.com>
navbar-default

changed from inverse to navbar-default

Signed-off-by: shawnsandy <shawnsandy04@gmail.com>
Semantic Cols

Add semantic cols demo section

Signed-off-by: shawnsandy <shawnsandy04@gmail.com>