According to Serhii Plokhy's Lost Kingdom, at a time of linguistic-nationalist tension, Mikhail Lomonosov prescriptively defined three styles:

the high style, to be used for the composition of epics, odes, and poems, was supposed to employ the vocabulary common to Church Slavonic and literary Russian; the intermediate style, to be used in dramatic works, was to rely on the vernacular but avoid colloquialisms; and the third, lower style, which admitted the language of townsfolk and peasants, was reserved for comedy.

The man is so famous that I can only imagine his plan had some influence. But to what degree did authors of the late 1700s follow these recommendations?