Header picture zooms in too much

[WTGM]

Hi,

Love the theme.

However, when I upload a recommended sized picture (2500x600 pixels), only a fraction of the picture is shown because it's zoomed in -- what's happening? I want the edges of the picture to display at the edges of the screen. I tried uploading a jpg and a png file to see if that made a difference, but got the same result.

Thanks.