Type ‘string’ is not assignable to type ‘”inherit” | “initial” | “unset” | “fixed” | “absolute” | “static” | “relative” | “sticky”‘

This is a workaround, but it is alright.
Some other solution is:

const mystyles = {
   position: 'absolute',
} as React.CSSProperties;

You can check back when this issue will be solved. Around TS 2.6 i guess, judging by milestones.