UI Design

https://www.creativebloq.com/how-to/20-best-ui-design-tools

https://medium.com/@tristaljing/4-best-web-ui-mockup-tools-for-free-89a1513c3fcd

https://careerfoundry.com/en/blog/ux-design/free-wireframing-tools/

CSS

Curves

https://freefrontend.com/css-headers-footers/