clicking on ".cross-og" removes class "open-nav" on ".navigation-overlay"
clicking on ".cross-og" removes class "darken" on "#root"
clicking on ".menu-link" removes class "open-nav" on ".navigation-overlay" no-prevent
clicking on ".menu-btn" adds class "open-nav" on ".navigation-overlay"
clicking on ".menu-btn" adds class "darken" on "#root"