Avoid global styles to break components

[Grsmto]

Bug Report

Describe the bug
In docz-theme-default some global styles are applied which are reaching components and breaking the styles on some scenarios:

*, *:before, *:after {
    box-sizing: border-box;
  }

All my components will receive box-sizing: border-box;.

These global rules could be easily avoided by using the box-sizing properties on the necessary elements directly.

A clear and concise description of what the bug is.
docz-theme-default global styles are leaking to consumer components.

To Reproduce
I guess this is self explanatory.

Expected behavior
Styles from docz-theme-default should not impact on consumer components.

I can provide a PR for this if maintainers think this is a valid issue.

[kylealwyn]

Also experiencing this on the dark theme and the global font color leaking into the live preview:

[jedrichards]

Agreed ... since this lib doesn't make any attempt to isolate styles between the component previews and the outer theme then the very least that should happen is that global styles aren't used in the theme.

The theme additionally includes normalize.css which can also have a global effect on component styles. It essentially forces you to use normalize.css in your apps too, since otherwise there's no guarantee components will render consistently in docz vs. your app. It's a shame because normalize is pretty bloated, and no longer really appropriate as a modern css reset.

Much better to make the theme CSS more robust and isolated, and reset theme elements individually as needed.

[mergebandit]

While this is one example, for non-trivial implementations / themes I think it could be a common problem in the wild.

Storybook mitigates this by wrapping each component in an iframe. We're working on a Storybook to DocZ bridge right now, and one of the things we're exploring is wrapping our components in either an iframe or potentially using shadow dom (yay component heights being respected!) to encapsulate each of the story components.

[transitive-bullshit]

Agreed w/ @mergebandit. The storybook-inspired solution to this would be wrapping the MDX React subtree for each page in an iframe that is wholly isolated from the global page.

What @Grsmto is pointing to in terms of CSS isolation is an important point. imho it's related to a larger issue of isolating the host / theme page from any specific page's contents. Since those contents can contain MDX and therefore can transitively include any JavaScript, there's no isolation guarantees for styles, HTML manipulation, or global JavaScript pollution. Practically, the most likely area to manifest issues would be from CSS pollution.

I think a general look into how to properly isolate host / theme styles & code from hosted / mdx styles & code would be great, though at the same time, I'm hesitant to introduce the extra complexity that an iframe layer would necessitate.

[jedrichards]

Using all: initial, possibly with help from a postcss plugin could be a practical way to achieve an element level CSS reset.

https://developer.mozilla.org/en-US/docs/Web/CSS/initial
https://github.com/maximkoretskiy/postcss-autoreset

[pedronauck]

Fixed on the new release v0.12.10 ✅

[jedrichards]

@pedronauck Would you mind clarifying what's been changed/fixed related to this issue in the latest release? I had a look through and couldn't find anything mentioned.

[pedronauck]

I removed normalize.css from theme default and the classes and styles applied to Playground are fixed too!

[kachkaev]

Looks like this bug still occurs in the latest version. I just cloned the repo and launched the basic example with just the following added lines to packages/docz-theme-default/src/styles/global.ts:

* {
  box-sizing: border-box;
}

Here's the result:

(notice gaps next to the resizer)

---

UPD: 💊 #578