Step 3 : Size your Grid
You now have your twelve columns displayed in your application. We want to set their size depending on the screen resolution : Let's start by defining the smallest screen : 0-576 px. Select all your GridCol (1 to 12) by holding Shift + Click, then go to the properties and look for "Size 0-576 px (xs)" and select 12. It means in this screen size, your grid will be displayed vertically.