JSS style guide is added

Author: codeShaurya

css/css_style_guide.md

@@ -2,7 +2,7 @@
 
 ## Semantics first
 
-Want to make text look big ? Think about the reason first, maybe it is a title and `<h1-6>` should be used. Maybe it is an important word, use `<strong>`. If it is a subtitle, use `body` and `overline` variant. Once the correct semantic is used, you may have a selector ready. Read the full Material Design guideline to design [Typogrrphy](https://material.io/design/typography/the-type-system.html#)
+Want to make text look big ? Think about the reason first, maybe it is a title and `<h1-6>` should be used. Maybe it is an important word, use `<strong>`. If it is a subtitle, use `body` and `overline` variant. Once the correct semantic is used, you may have a selector ready. Read the full Material Design guideline to design [Typography](https://material.io/design/typography/the-type-system.html#)
 
 ## Sub-categorize CSS
 
@@ -11,12 +11,16 @@ Want to make text look big ? Think about the reason first, maybe it is a title a
 3. Site Category CSS (Consistent visual for a site category (news, weather))
 4. Page Specific CSS (used only on 1 page)
 
-By putting the most common CSS in company wide css, you get visual consistency for free, and best code reuse. Alternatively with SASS or LESS, one could declare site-wide variables and import those where required. 
+By putting the most common CSS in company wide css, you get visual consistency for free, and best code reuse. Alternatively with SASS or LESS, one could declare site-wide variables and import those where required.
 
 * 1 Component, 1 CSS
 
 Can be further extended on individual site categories or pages.
 
+## JSS
+
+One best method to implement subcategorize CSS is to use JSS. JSS stands for Javascript Style sheet. In JSS, CSS is written in a javascript object and then it is parsed by parse in actual css. Write one JSS for one component. Check [official documentation of JSS](https://cssinjs.org/?v=v10.0.0)
+
 ## Selectors
 
 Should be as short as possible. Use the element selector only when it makes sense (e.g for site wide styles) . Use descendant, and child selector when the associated markup also follows this hierarchy