Rashi on Exodus
לעמת קלעי החצר [AND THE SCREEN…] ANSWERING TO THE HANGINGS OF THE ENCLOSURE — i. e. according to the measure of the height of the hangings of the enclosure.
Siftei Chakhamim
Like the measurements of the curtains of the courtyard. The word לעומת is ordinarily used for something that is “across from.” Yet, the curtains were not across from [the screen], but at its sides. Thus Rashi explains: “Like the measurements.” I.e., the screen should be the same size [as the curtains].