So I made an event card in Illustrator and then exported it, but the PNG file Illustrator has created has some grey lines at the top, the bottom, the right and the left of the card. I uploaded the event card on Facebook to see if they are still there, but they are, and I don't know what are those lines. Could you guys help me? (Sorry for my english, just learning the language.)
Apparently, the objects that make up your background don't fully reach to the border of the artboard you've exported into your
png. To reflect what it sees as a tiny gap, Illustrator anti-aliases your coloured backdrop over its white background, yielding a grey pinstripe.
Try and make your backdrop larger than the artboard. That way, Illustrator will see colour all the way to the edge, see no need to anti-alias and make a proper