a responsive grid on several columns

syntax 1 : {up flexauto=x_desktop | tablet=x_tablet | mobile=x_mobile }content{/up flexauto}syntax 2 : {up flexauto=x_desktop-x_tablet-x_mobile }contenu{/up flexauto}
x=1 à 12 is the number of columns on large screen and tablet. 4 on mobile.