Modified color variables and heading margins

- Changed all the color variables to have an HSV value of 60% except for
@colorOrange which is OK as it is. This will make the colors tolerable
in both dark and light background if used as text and dark and light
text if used as background.
- Added the color variable @colorgrey which is at 50% HSV value.
- Modified the headings to have equal top and bottom margins.
- Changed variable @fontHeaders to @fontHeadings