Guest Russ is right.

To fine tune positioning find the twelveth string harmonic for each sring (that runs from the nut obviousl) and fidle with the bridge until the harmonic is exactly above the 12th fret.

because the strings vary in thickness, the thinist sting will prouduce it's correct harmaonic possition closser to the neck than the thicker 4th. That's why bridges are angled slightly.

This fine tuning keeps the strings in tune together as you progress up the fretboad.

Finer tuning is getting the possition of the harmonics for the 5th and 7th frets adjusted.

Wrinkles