Pod request access landing page using HTML and CSS

In this project in mobile responsive I was confused about using mix-blend-mode and I just know how to use it when I finished my HTML schematic. Then I decided to not use it and just setting the opacity instead and it works. I think the mix-blend-mode is use in parent element but if I use in body or container, it will blend all child in body and container. So, if anyone have suggestion, please let me know. Thank you :)