Help Adjusting Padding and Width on Navigation Menu

I’m new to this, so apologies if I’m missing something obvious. I’ve searched this forum and youtube tutorials and tried everything but cannot make it happen.

I have a navigation menu with two problems. The first is that the text for each page title in the menu navigation occupies the entire horizontal space, with the result that there is no spacing at all between the separate page titles on the navigation menu. The second issue is the menu does not extend to the full width of the page.

I am using a Twenty Eleven Child Theme. Prior to creating the child theme I was playing around with menu items in the parent theme. I suspected I had changed some code in the parent theme that might be impacting the child theme, however even uninstalling and reinstalling the parent theme didn’t solve it.

Any ideas would be appreciated.

Thanks in advance