I know of a family whose father demands all the women in the home to wear long dresses with long sleeves every day of the year. Three-quarter length dresses and sleeves. They call this the Marian way to dress modestly. They are Catholic and are telling my family (my sisters and nieces) not to wear pants any longer or any kind of shorts.
Modesty is a virtue that encompasses more than clothing choice, although our clothing choices are a practical working out of the virtue of modesty. Modesty is defined by the Catechism of the Catholic Church (2522):
Modesty protects the mystery of persons and their love. It encourages patience and moderation in loving relationships; it requires that the conditions for the definitive giving and commitment of man and woman to one another be fulfilled. Modesty is decency. It inspires one’s choice of clothing. It keeps silence or reserve where there is evident risk of unhealthy curiosity. It is discreet.
The Church does not mandate any one clothing choice for women – or for men, for that matter. According to the CCC (2524):
The forms taken by modesty vary from one culture to another. Everywhere, however, modesty exists as an intuition of the spiritual dignity proper to man. It is born with the awakening consciousness of being a subject. Teaching modesty to children and adolescents means awakening in them respect for the human person.
So, while this family’s clothing choice is one modest option, it is not the only option and should not be presented “the Marian way” of modest dress, as if this choice was the only clothing that would be approved for women by the Blessed Virgin Mary.