Pertinent to today's feast is the typology of Mary as the Ark of the (New) Covenant, put together by Catholic author and apologist Steve Ray:
Inside the Ark
Our second point of consideration for today's feast day comes on the heels of my consideration of the liturgical colour rose, and that is Gregor's consideration, made two years ago, about the special permission for the use of blue as a liturgical colour in certain parts of the world, including in Spain for today's feast.
Gregor provides various examples of these rare blue vestments in his 2009 piece, The Immaculate Conception: Liturgical Blue; here is one of them: