Frontend Верстка (β)

Position, Z-Index

https://developer.mozilla.org/ru/docs/Learn/CSS/CSS_layout/Positioning (Novice)
https://web.dev/learn/css/z-index/ (Novice)
https://developer.mozilla.org/ru/docs/Web/CSS/CSS_positioned_layout/Understanding_z-index/Stacking_context (Intermediate)
https://philipwalton.com/articles/what-no-one-told-you-about-z-index/ (Intermediate)