I was reading this text: "Эта куртка мне нравиться, только цвет не мой. Нет ли такой посветлее?"
Also before some weeks I said without even thinking to client: "У нас тоже что-нибудь подешевле ".
I was taught that in order to form the Сравнительная степень we just remove the окончание -ний or -ный and we put double e.
At some point I was confused because some adverbs are formed by adding the по at the beginning of the word (e.g. по-настоящему, по-новому, по-разному). Of course посветлее and подешевле are not adverbs.
My question why the normal Сравнительная степень (i.e. светлее and дешевле) is not used instead of посветлее and подешевле in the sentences?