@David, Moderator posted:
Thank you for your kind words, Nousher.
The separation of "and just as ingenious" from the phrase with which it is coordinated ("As vital") gives it the quality of an afterthought, of something which the speaker decides he wants to add in the process of speaking.
In other words, the clause describing "igloos" ("which permit the Innuits to live in reasonable comfort in an icy land") may strike the speaker as making igloos ingenious, and he may realize that "ingenious" also applies to Innuit clothing.
The sentence is a complicated one—uncommonly complicated. Native speakers don't go around casually inverting their sentences, separating and delaying predicates as afterthoughts, and using multiple nonrestrictive relative clauses.
So don't feel bad if you find this sentence a mindbender. Probably any other learner would, too. The problem may be simplified by trimming off the relative clauses and using normal sentence order: subject—copula—complement:
(A) Their winter clothing is as vital and just as ingenious as their igloos.
(B) Their winter clothing is as vital as their igloos and just as ingenious.
An alternative to parsing "and just as ingenious" as a postponed conjunct to "as vital" is to parse it as a reduced clause, likewise added as an afterthought. That is, (B) can be seen as deriving either from (A) or from (C):
(C) Their winter clothing is as vital as their igloos [are] and [is] just as ingenious as their igloos [are].
Sir, thanks for clearing my doubt.