You will find all the styles for these components insrc/assets/jss/nextjs-material-kit/components/parallaxStyle.js.
If you want a nice parallax like that in our demo pages, you can add the following code at the beginning of your page.
import Parallax from "/components/Parallax/Parallax.js";<Parallax filter image={require("path/to/your/image")} />Parallax.propTypes = {
  className: PropTypes.string,
  filter: PropTypes.bool,
  children: PropTypes.node,
  style: PropTypes.string,
  image: PropTypes.string,
  small: PropTypes.bool,
  // this will add a min-height of 660px on small screens
  responsive: PropTypes.bool
};