clicking on ".forms__button_zvonok" adds class "overlay-open" on "#overlay"
clicking on ".forms__button_zvonok" adds class "forms_zvonok-open" on ".forms_zvonok"
clicking on ".forms__button_close, #overlay" removes class "overlay-open" on "#overlay"
clicking on ".forms__button_close, #overlay" removes class "forms_zvonok-open" on ".forms_zvonok"