Practical CSS cases from real projects: layout, stacking contexts, z-index, positioning, overflow, responsive interfaces, and less obvious rendering problems in complex components. I focus not only on the fix, but also on the browser behavior that caused the issue.
I changed a margin or padding in SCSS, refreshed the page, and nothing happened. This is the practical debugging flow I use to trace the problem through source, build, compiled CSS, DOM, cascade, stylesheet order, and only then cache.
In the ICanUp editor, Media Explorer opened above Content Blocks, yet parts of the underlying editor could still render over the modal layer. This article explains why a huge z-index is not always enough, how CSS stacking contexts work, and why overlays need a clear layer contract instead of arbitrary numbers.