htmls for the main menu. Also fixed the first page of Modelling and
Simulation package of html. Also fixed the stylesheet.css.

Issue-Ref: 4007
Issue-Url: https://af3-developer.fortiss.org/issues/4007



Signed-off-by: Saad bin Abid <abid@fortiss.org>

stylesheet to be applied to the rest of the html pages.

*

Issue-Ref: 4007
Issue-Url: https://af3-developer.fortiss.org/issues/4007



Signed-off-by: Saad bin Abid <abid@fortiss.org>