Width content with the news

Hello everyone,

I need your help how to change the width content area of the news. I set it as 1000px as slider image – these news should be too in content area with the slider image but I don’t know why there is few pixels on the right and the left side – I can’t search it.

Also, how do I should make the same image size for posts? I would like to have 320x200px featured image per post.

Best