I don't really get it. I use the function add_image_size to add a custom size so that I can display a feautred image with the nickname of the custom size. Using add_image_size I set the height to 300px and I look for the value of the width so that the image spans all the way across. But I can't make it, past 1100 the image doesn't stretch anymore, and also when I use smaller values such as 600 for the width I see that it also affects the height.
Why is that? Aren't the width and the height supposed to be independent? And what is the correct way to set the values of the width and the height so that the featured image will span all the way across the browser with a certain height?
Thanks in advance