Autopilot: What does the "move CSS inline" option do?
Popular email clients like Outlook and Gmail strip out CSS <style> in the <head> portion of your email's HTML. You can overcome this limitation by inlining your CSS.
We automatically move your CSS inline when you import an HTML template, however you can turn this off if you wish to do so. For best results, we recommend leaving this option turned on.
Learn more about CSS inlining here.