CSS rule has a big side effect

First of all, thanks for your work, it helps me a lot.

https://github.com/akiran/react-slick/blob/48c93ed36cfb58991e6bf4d34a1a588094281d12/docs/slick.css#L89-L92

if there is a complex structure of slide, not only a image and some text, this rule has a big side effect.

---
And a question:

Is there some config for slide split rule, like:

if I have 9 slide, four as a group, then my setting is `slidesToShow: 4, slidesToScroll: 4,`, it behavior is
```
screen 1: 1,2,3,4
screen 2: 5,6,7,8
screen 3: 6,7,8,9
```
I know this is better solution for most case, it more beautiful, but for sometime, I just want only NO. 9 for screen 3, I can't find the config for this. Did i miss something?