A template of macro {control} to display site navigation. Import {latte} block from the template stored in folder 'control' to 'menuControl.latte' before condition of variable $menuDepth using macro {import '../path-to-latte-template'} and declare this block as {include #m-nav-header}. There are available hooks to customization CSS classes of list, item and link.
The variable 'submenu' has options 'm-nav-dropdown' and 'm-nav-mega' representing style of submenu.
{import '../path-to-latte-template'}
{include #m-nav-header, submenu => 'm-nav-dropdown', menuClass => '...', itemClass => '...', linkClass => '...'}Do not forget set CSS property position: relative to one of parent elements, which define megamenu width.