Docs/mkdocs styling (#38)

* docs: refine mkdocs theme styling

Add light/dark palette toggle and premium typography via custom CSS.

* Update theme.css

* Update theme.css

Author: mheidari988

docs/_assets/theme.css

@@ -4,7 +4,7 @@
 }
 
 html {
-  font-size: 15px;
+  font-size: 16px;
 }
 
 .md-typeset h1,