Having a sticky post image size issue with the Twenty Fourteen template. Need some guidance on where to make this edit. The featured image on my Sticky post is 1240 x 520, which should be large enough, but I am still seeing the image get resized smaller with gray area around it.
Which file - specifically - should the edit be made in? I have not used child themes, and prefer to do it without going in that direction if possible, unless it is rather painless.