lines within the main menu – to be removed or color changed

Hi,

I was wondering, can i change the vertical lines within the main menu/the vertical dividers between the links? I would like no black or grey lines, just white spacing between the links
Have a look at the screenshot.
Do i change the colour under theme settings/customize color, or is there an option for this? or Css?

Also how do I change the border color/border container lines for all of the boxes throughout the template/web site, say a light blue etc?