activeClass () {
      const classes = Glide.settings.classes
      const slide = Components.Html.slides[Glide.index]

      if (slide) {
        slide.classList.add(classes.slide.active)

        siblings(slide).forEach((sibling) => {
          sibling.classList.remove(classes.slide.active)
        })
      }
    }
Sets active class to current slide.

@return {Void}