You can use your own HTML and CSS code but with a few restrictions.
1- Put your html in
var html; and your css in
var css; in lines 1 & 2 in
2- Your HTML code must only contain strings inside " " double quotes and not ' ' single quotes.
3- Your CSS cannot have any nested elements such as media queries or Sass/Less code.
4- You can also inject HTML with script tag inside but keep in mind that a condition must be added inside your script tag to only allow it to run once and cannot manipulate the DOM till code injection is complete.
5- HTML tags that don't have closing tags might affect the indentation of the code wrriten.