Breaking Changes & Regressions

While replacing the custom HTML and CSS parsers and implementing support for newer standards, we'll eventually break something. This issue should help track intentional breaking and unintentional regressions. We could try and fix all the regressions when they're introduced, but in order to allow for faster contributions, which may include some of these fixes already, it makes more sense to move forward and document them here.

## Breaking Changes

- Rendering blocks inside inline elements will lead to different behavior, as HtmlKit auto-closes the invalid HTML
- `corner-radius` is replaced with the official `border-radius`
- `background-gradient` is replaced with the official `linear-gradient`

## Regression

- [ ] Consecutive `
` tags don't lead to empty lines

The issue names no files, tests, or entry points. Reproduce consecutive
tags in the HTML renderer, then verify that they produce the expected empty lines while ensuring the listed breaking changes remain documented.

Written by the indexing model from the issue text.