Thank you Kathryn! I did that and made the feature image of a draft post 1300 x 975, but I am still seeing it as blurry when I look at it through my phone. I am trying to figure out how to make it so that the image looks sharp when I look at it through the mobile site. I tried making the feature image smaller so that it wouldn’t appear blurry on the mobile site, but then I got the black bar above and below the image, which is what I don’t want.
Is there a magic ratio that I should aim for? Thanks in advance for your help!