Hi midhat
I added this custom css rule to show the menu:
.com_eshop .t4-megamenu.collapse {height: auto;}
About the mainnav full screen, it due to the style of this template, it is set to be full width by default. You will have to customize to show it in fixed width:
This code will help to override it:
.layout-home-horizontal .t4-header-inner, .layout-default-horizontal .t4-header-inner{
position: relative;
}
however, you will customize style of megamenu again.