What is the ruling on the stipulated dowry if a guardian other than the father contracts the marriage for less than the customary dowry?

Primary text

If a guardian other than the father contracts the marriage for less than the customary dowry, the marriage contract is valid, but she is entitled to the customary dowry (*mahr al-mithl*). This is because the invalidity or omission of the specified dowry does not affect the validity of the marriage contract itself. She receives the customary dowry because it represents the value of her person, and the guardian does not have the right to reduce that value.