Smart Builder utilizes a styled-component package to add style to your page components.

To learn more, visit the documentation in GitHub:

https://github.com/styled-components/styled-components

Unbounce’s Design Guidelines for External Developers can be found as a Figma file here:

https://www.figma.com/embed?embed_host=notion&url=https%3A%2F%2Fwww.figma.com%2Ffile%2FZhhNE3yqbxD1FZhpHSSFk5%2FDesign-Guidelines-for-External-Devs%3Fnode-id%3D0%253A1