Which Gunas are important for marriage?

For approving a marriage, there must be not less than 18 Guna matches between the bride and the grooms horoscopes. If the matching Gunas are less than 18, then the proposed match is not approved. If 18 to 25 Gunas match, then it is demed as a good marriage. A best match ensues when 26 to 32 Gunas match.