global color changes in child theme (Penscratch theme)

Although I’m using Penscratch theme, I think my question would relate to others trying to modify the look of a theme using a child theme. I’m replacing a color used in the Penscratch theme (#1c7c7c, a medium teal color) with a shade of gray (#666666). I’ve used a text editor & searched the parent css file for all mentions of the original color, copied those commands to my child css file and changed the color to #666666. That was a lot of work, and I’m not sure if I add widgets if these color schemes will carry over (I’m guessing that they won’t). So, my question is two-fold: 1) how to I make global color changes in my child theme that will withstand updates and additions of new widgets, etc., and 2) how do I make global changes like this in an easier manner? Is it through the child’s php file? I’d love to know how to use a global ‘replace’ command…

Any resource references, general comments are welcome.