/* * vars: --textcolor * selectors: body */ :root { --textcolor: black; } body { font-family: sans-serif; font-size 16px; color: var(--textcolor); } /* use titlecolor if defined in project, otherwise textcolor, which is defined here in lib but may be overriden in project; fall back to */ h1 { color: var(--titlecolor, --textcolor, black) }