To adjust only colors or only thickness, delete the appropriate section in the code (see comments). If necessary I'll make a separate style for each.

If you're just customizing the default YouTube ratings bar colors (to make the dislikes color red, for example) and want to keep the same thickness, use 2px as the thickness.

To customize the YouTube Ratings Bar with Like Strength script, use http://freestyler.ws/style/76421/youtube-ratings-bar-with-like-strength-customized by lednerg@userstyles

If you install this style and then want to choose different settings, just delete it and re-install. You will only be given the option to update if the style code has been updated.