CSS code for background image 100% fill


website is importingtips.com

I have added an image to the background of the latest posts widget. see image below


this is the css code I have used

background: url(“http://importingtips.com/wp-content/uploads/2013/12/recent-post.jpg”:wink: no-repeat scroll 0 0 #000000;

I am using a responsive design and when the site screen size changes the widget box increases in size but the background image remains the same size.

see example link below


What css code can I use to have the background image stretch to 100% horizontally and vertically of the widget area when ever it changes with the screen size?