Let's have a small info about the CSS. CSS means Cascading Style Sheets. CSS is very helpful for making site beautiful and attractive and in other way we can say that CSS is undividable part of current websites.
There are three types of CSS like Internal CSS, Inline CSS and the last but not the least External CSS. Mostly people are selecting the external css for better structure. Latest structure of the CSS is CSS3 version which is containing Animation, Transitions, Transformation, Easing etc.. There are lots of new things new CSS3 which are helps to developer for the creating better and beautiful site.
Now this days there are pre compiler versions are coming there like Sass and Less which are converting CSS to Dynamic CSS. In that precompiling css there also possible with taking dynamic variables and media queries. With the help of that now the site can be more fast and speedy comparing to old school times.
So we can say that without using of css the website layout is only skeleton and to make it beautiful the using of CSS is must.