If a noun has no article, (e.g. bei nicer Shop! or heißes Top), the adjective takes the ending of a definite article.:  der – nicer, das – heißes, den – blauen, die – blaue, dem – schönem, ...

It only differs in the masculine and neuter genitive case. Here the adjective ending is -en and the noun gets the ending -(e)s.