Fallback First — Progressively Enhance

You may have noticed that the default option for the Design For is called Fallback First. This mode is intended to apply styles to all browsers. So, for example, if you want to create styles for IE11, you add all of your styles to this mode making how you want your page to look without any modern features.

Once you have the base style for your page (this fallback first), you can progressively enhance your page with the other styles like display grid, blend modes, etc…