Why we’ve CSS:
I will not go much deeper into the history of CSS and why it is there in the first place but in the beginning, CSS was just for type and colors, that’s it. Then we’ve to rely on problematic Floats and Absolute Position to position elements or section. Until recently they are forcefully moved toward layouts, thanks to flexbox and grids.
What’s you’ll see in every next version
Every new version of CSS bring two things to the table. First and foremost it helps reducing the use of images with it’s new properties. Remember the old days of adding rounded corners or drop shadows. But with CSS3 border-radius, gradient, box-shadows you can achieve more than before. We’ll see more and more of these things to help servers sent data smaller and quicker. Not only CSS can do that, you can learn more about it here and here