Add style improvements for session element
Add style improvements for session element

GDGKoreaCampus/homepage,GDGYangon/gdg-yangon-devfest-2015-website,gdg-eskisehir/wtm17,GDGYangon/gdg-yangon-devfest-2015-website,GDG-Nantes/devfest2017,GDG-Ukraine/hoverboard,GDG-Ukraine/hoverboard,gdg-eskisehir/wtm17,GDG-Nantes/devfest2017,GDGKoreaCampus/homepage