This is a follow-up from a private maintainer discussion (https://github.com/orgs/just-the-docs/teams/maintainers/discussions/11?from_comment=12). The cliff's notes for the public are: we believe we are not currently GDPR-compliant in how the docs site itself serves analytics.

For now, we'll disable analytics; we don't use them anyways. We will then:

- add analytics and the relevant banner to the regression test repository
- in the future, workshop a built-in solution for JtD users to be GDPR compliant
- optionally, clarify the role of users of this theme (their responsibility is to make their sites GDPR compliant)(

Hi everyone, this is a large refactoring PR that looks to **modularize site components** following the discussion in #959. At the top-level, it:

- moves icons, the sidebar, header (navbar, search, aux links), footer, and mermaid components of the `default` layout into their own `_includes`
- creates a new `minimal` layout that does not render the header or sidebar as a proof-of-concept for the composability of components
- documents all existing and new layouts (including vendor code) in the "Customization" section 

An important goal of this PR is for it to be **just code motion and flexibility**: there should be **zero impact** on the average end user that only consumes the `default` theme.

The next few sections go in-depth on each of the listed changes.

### new components

The `default` layout contains a "list" of all relevant components. Importantly, some of these components have sub-components:

- the header is split into the search bar, custom code, and aux links
- the icons include imports different icon components, some of which are conditionally imported by feature guards

There are also candidates for future splits and joins:

- the sidebar could be split into navigation, collections, external link, and header/footer code
- the "search footer" could be joined with other search code, which would make it easier to "include search" in one go; *however, this is a markup change*
- @kevinlin1 has pointed out that there is some leakage between the sidebar (which computes parents/grandparents) and the breadcrumbs (which needs them to render). He's graciously added a bandaid fix to `minimal` (which does not render the sidebar). However, in the long term, we should either:
    - calculate this in a parent and pass the information to both components
    - change how this works entirely (which may happen with multi-level navigation)

@pdmosses has done a great job outlining this and more in his [Modular Layouts test site](https://pdmosses.github.io/modular-layouts/docs/main/).

### minimal layout

Based on @kevinlin1's use-case in just-the-class (see: his [Winter 2023 CSE 373 site](https://courses.cs.washington.edu/courses/cse373/23wi/)), we've created a first-class `minimal` layout that does not render the sidebar or header.

In a [comment](https://github.com/just-the-docs/just-the-docs/pull/1058#discussion_r1057015039), Kevin has indicated that we can re-add the search bar in the minimal layout; however, it seems like this would be a code change. I think we should punt this to a future issue/PR.

@pdmosses has also discussed the confusion of `minimal` as a layout and its meaning in inheritance. I've added a note in documentation to clarify the (lack of) inheritance relationship.

### documentation

I've written documentation in the "Customization" page / [Custom layouts and includes](https://deploy-preview-1058--just-the-docs.netlify.app/docs/customization/#custom-layouts-and-includes) section explaining:

- generally, that we use includes/layouts (and pointing to docs)
- the `default` layout and its constituent components (with a warning about name collisions)
- creating alternative layouts with `minimal` as an example
- the inheritance chain of layouts and the vendor layouts that we consume

I've also created (and linked to) a [minimal layout test](https://deploy-preview-1058--just-the-docs.netlify.app/docs/minimal-test/) that is currently a copy of the markdown kitchen sink but with the minimal layout. I think there's room to improve this in the future.

### future work

I think there's a lot we can do. Let me break this into various sections.

Potential follow-ups before `v0.4.0`:

- re-including search in `minimal` (anticipating a minor code change)
- fixing the leakage of parent/grandparent information between the sidebar and breadcrumbs (anticipating no end-user code change, but good to evaluate separately and discuss)
- heavily document this in the migration guide (#1059) and in our RC4 release docs
- improve semantic markup for components (ex `main`, `nav`)

Related work in later minor versions:

- split up components into smaller components
- allow users to easily customize new layouts using frontmatter (see @kevinlin1's [comment in #959](https://github.com/just-the-docs/just-the-docs/issues/959#issuecomment-1249755249))

Related work for `v1.0` (i.e. a major breaking change):

- rename and better categorize existing includes
    - standardizing the "custom" includes
    - moving other components to the `components/` folder (ex `head`, `nav`)
    - potentially: less confusing naming for various components
- potentially separate the search and header as components, so that they are completely independent 

Tangentially related work:

- more flexible grid (see @JPrevost's [comment in this PR thread](https://github.com/just-the-docs/just-the-docs/pull/1058#issuecomment-1363314610))
- a formal [feature model](https://en.wikipedia.org/wiki/Feature_model) of JTD, documenting feature dependence (see @pdmosses's [comment in this PR thread](https://github.com/just-the-docs/just-the-docs/pull/1058#issuecomment-1365414023))
- better annotate new features (motivated by writing these docs)
    - we should add "New" to new features :) 
    - we should note when a feature was introduced (I think this is a core part of most software documentation)
    - we should annotate things that are "Advanced" in so far as the average Just the Docs user will not use them / they require significant Jekyll knowledge


--- 

Closes #959.

Context: https://github.com/just-the-docs/just-the-docs/pull/1029#issuecomment-1369613443.

This PR fixes three bugs:

# first bug

When revising my last PR #1086 I realised a slight bug in the code-copy PR #945 , my change to the css ignored a case. This PR is a hotfix and

Before PR #945:
![image](https://user-images.githubusercontent.com/26844016/209864912-2fe8e5a9-f21e-40c7-aa0d-65050196f4ee.png)

![image](https://user-images.githubusercontent.com/26844016/209864950-c315cef1-36ee-4356-91b2-db159cf3806f.png)

After PR #945:
![image](https://user-images.githubusercontent.com/26844016/209864524-70a8b095-056a-464b-9ff7-fd31397492ba.png)

![image](https://user-images.githubusercontent.com/26844016/209864558-9fd7a5d3-a965-4aa4-af62-a56846e331b3.png)

Fix:
![image](https://user-images.githubusercontent.com/26844016/209865514-a9921096-b852-4402-8272-b76908851ad6.png)

![image](https://user-images.githubusercontent.com/26844016/209865550-d7842507-74fc-4f21-b407-9b8917df1fd8.png

)

# second bug

> @simonebortolin @mattxwang I'm trying to write some regression tests for this feature.
> 
> If I use GitHub's copy button to copy the following plain text, it preserves all the spaces:
> 
> ```
>  1 leading space
>   2 leading spaces and 2 trailing spaces  
> 3   internal spaces
> 4 trailing spaces    
> ```
> 
> Using the new copy button with the same text in this PR branch of JTD gives this:
> 
> ```
> 1 leading space
>    2 leading spaces and 2 trailing spaces  
>  3   internal spaces
>  4 trailing spaces
> ```
> 
> It appears that the leading space from line 1 has been removed, and inserted on all the other lines. Moreover, the 4 trailing spaces have been removed.
> 
> BTW, #924 didn't give a precise requirements spec, but mentioned the Microsoft docs UI; @mattxwang mentioned also the GitHub UI. It would be helpful to add a functional spec of what the JTD copy button is supposed to do, as a basis for regression tests.
> 
> I'm not aiming at a rigorous test for the UI. Personally (using Safari at the default mag) I find the clipboard icon too small: it just looks like a box, and I can hardly see that there is a clip at the top. But I don't have a suggestion for a better icon.

# third bug

When I re-read the code after the second bug, I noticed a bug that it does not always select the text field to be copied correctly  (in case there are also line numbers) is copied:

```
1
2
3
4

	
# Ruby code with syntax highlighting and fixed line numbers using Liquid
GitHubPages::Dependencies.gems.each do |gem, version|
  s.add_dependency(gem, "= #{version}")
end
```
instead of 
```
# Ruby code with syntax highlighting and fixed line numbers using Liquid
GitHubPages::Dependencies.gems.each do |gem, version|
  s.add_dependency(gem, "= #{version}")
end
```

Co-authored-by: Matt Wang <matt@matthewwang.me>

This PR corrects the change to `/_sass/labels.scss` made in 551398f9. This change tried to set the `padding-**top**` property to **two** values rather than set the `padding` property to these values (to represent the vertical and horizontal padding values).

* Fix stylelint "declaration-block-no-redundant-longhand-properties"

Co-authored-by: Matt Wang <matt@matthewwang.me>

Bumps [stylelint](https://github.com/stylelint/stylelint) from 14.16.0 to 14.16.1.
- [Release notes](https://github.com/stylelint/stylelint/releases)
- [Changelog](https://github.com/stylelint/stylelint/blob/main/CHANGELOG.md)
- [Commits](https://github.com/stylelint/stylelint/compare/14.16.0...14.16.1

)

---
updated-dependencies:
- dependency-name: stylelint
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Avoid the need to add a link to favicon,ico when editing `_includes/head_custom.html`, and avoid creating an invalid favicon link

- Remove the content of `_includes/head_custom.html`
- Add code to `_includes/head.html` to create a link to an existing favicon,ico
- Add an explanation of favicon_ico to docs/configuration.md
- Remove the example of `includes/head_custom.html` and add an explanation of what the `<head>` element automatically includes

Avoid Liquid failure when no pages with titles

Fix issue #1085

The user's config specified collections (incorrectly). Trying to build the site resulted in Jekyll failing due to a Liquid error. The error report did not suggest the cause of the error.

Liquid fails with division by 0 when title_pages_size is 0. This fix guards that code by checking that title_pages is non-empty.

To test:

1.  Specify a Jekyll collection with no pages, and specify it as a JTD collection.
2. Build the site.
3. Check that the specified collection has no nav links to pages.

Fix two bugs in customization docs

- custom favicon docs were not wrapped in `{% raw %}` tags
- the "new" annotation for color schemes had an extra whitespace, and so the CSS class was not applied

* docs(collections): Add warning about mandatory `_`-prefix

* Apply recommended wording

Hello everyone, this is my implementation for the copy button on the snippet (requested in #924)

The implementation is made 100% javascript as with or without a jekyll template modification you still have to execute some javascript code, and I consider it the best choice.

the button only appears if the mouse is over it, to allow the entire line to be read

the important CSS changes were made to make the copy button work even in the long code situation:


![image](https://user-images.githubusercontent.com/26844016/187731472-d4bf7828-2356-4d94-9c2d-9db863228f5f.png)

to avoid this:

![image](https://user-images.githubusercontent.com/26844016/183292313-d7f73d7d-58c0-4c7b-b5ba-e08bd285514b.png

)

Co-authored-by: Matt Wang <matt@matthewwang.me>

Relatively self-explanatory, pulled out of #1058

Context: #1079.

Context: #1074, #1076. I think the problem is likely with `@use "sass:math";`; the stock pages image doesn't contain an up-to-date enough version of SASS. I've instead replaced just that instance with a runtime `calc()` operation, which *should* get optimized away by the compiler (see: [SASS docs](https://sass-lang.com/documentation/breaking-changes/slash-div#transition-period)).

---

Original PR body:

> @pdmosses noticed that we have deprecation warnings on some of our SASS code. After testing locally, all of them have to do with using / as division in SASS, which is [deprecated](https://sass-lang.com/documentation/breaking-changes/slash-div) (since there's some lexical ambiguity).
> 
> SASS has a nifty [migrator tool](https://github.com/sass/migrator). I used the migrator piecewise on each deprecation warning (since the global usage fails on some liquid code). Upon manual inspection, I think there are no false positives. Running bundle exec jekyll serve after a fresh install and bundle update no longer emits any warnings.

Closes #1070.

This PR:

- updates `jekyll-anchor-headings` to `1.0.12`; this was a simple copy-paste
- updates `lunr.js` to `2.3.9`; this was a bit more involved:
    - I didn't see a minified build in the repo, so I ran it through [DigitalOcean's minifier](https://www.digitalocean.com/community/tools/minify)
    - copyright notices weren't properly included in the previous minified build, so I:
        - include an actual copy of the original MIT License for `lunr.js`
        - includes proper attribution for other functions, which include derivative works

There's a tiny bundle size increase in `lunr.js` due to the comments, but I think that's reasonable given that it's related to licensing; still trivial in the grand scheme of things.

As an aside: it would be neat if we could include minification as part of the build pipeline instead!  

@pdmosses noticed that we have deprecation warnings on some of our SASS code. After testing locally, all of them have to do with using `/` as division in SASS, which is [deprecated](https://sass-lang.com/documentation/breaking-changes/slash-div) (since there's some lexical ambiguity). 

SASS has a nifty [migrator tool](https://github.com/sass/migrator). I used the migrator piecewise on each deprecation warning (since the global usage fails on some liquid code). Upon manual inspection, I think there are no false positives. Running `bundle exec jekyll serve` after a fresh install and `bundle update` no longer emits any warnings.

Closes #1073; blocked by #1072 (CI failure).

This PR adds a `deploy.yml` to match [what's in our template repository](https://github.com/just-the-docs/just-the-docs-tests). I think it would be a great idea for us to match parity, especially:

- so that it's easier for us to help users & debug
- so that if we move to Jekyll 4 (likely soon), the transition is seamless
- so that we can explore adding custom items to the build step

Before merging this, we'll also need to change the source of the Pages deploy to actions (from the current branch deploy).

tl;dr: 

- replaces `jekyll/jekyll` with actions-native container
- changes Jekyll version targets to be explicit: `[3.9, 4.3]`
- fixes CI bug from today

I've **temporarily changed the branch protection rules** so we can merge this PR in.

## Motivations

A handful of motivations for me doing this:

- immediately: in writing #1071, I noticed that our CI is broken; this is due to an issue with the `jekyll/jekyll` container (see below)
- generally: I would like to make our CI as close to what our users would be using; I think the vast majority of our users use pages or actions, rather than the container itself
- nit: building `3.8.5` is *really slow* (takes ~ 3 minutes), and now each matrix strategy takes ~ 30 seconds with no cache!

More on each of those points now!

### Immediate Problem: `sass-embedded`

Starting today, CI fails on `main`. #1071 has one example ([CI log](https://github.com/just-the-docs/just-the-docs/actions/runs/3752287338/jobs/6374267086)), and I was able to repro this on a whitespace change with the `README`.

Several notes:

- building locally, with pages, or with Netlify does not fail; for example, the deploy preview for #1071 still works
- the error has to do with native extensions (of which `sass-embedded` is one of them) not being built properly for musl c linux; changing the pinned version of `sass-embedded` to a previous version does *not* resolve this problem
- it's not transparent what has changed: the `jekyll/jekyll` image itself has not been updated in over a month, but, something in the container (which was not pinned) must have changed and forced an error with compilation

Given that *our users* won't encounter this problem, this reads easily as a CI problem to me - we should resolve our pipeline (and not change user code/artifacts).

### Bigger Picture: `jekyll/jekyll`

Disclaimer: I have never really liked that we use `jekyll/jekyll` as part of our CI pipeline. Let me outline why and why I think this change is a good idea.

Broadly, our CI should closely match how our users use just the docs. After fielding support requests, looking at our big players, etc., I think the most common deployment methods are:

1. using native GitHub Pages. Recently, [GitHub has moved this to use GitHub Actions and their containers](https://github.blog/2022-08-10-github-pages-now-uses-actions-by-default)
2. using GitHub Actions explicitly, like what's provided in our template
3. "out-of-the-box" CD from providers like Netlify, Vercel, or Fly

In contrast, I have met few users using the `jekyll/jekyll` or `jekyll/builder` containers; of course, this is still anecdotal.

Thus, I think our CI should match the common denominator in the vast majority of our user base, which is *not* using the community container, but instead a standard linux container + bolting on Ruby tooling. Given that GitHub Pages is likely our biggest userbase, I think we should match it - which means, using Actions-specific containers (what's in this PR).

Furthermore, I think it's more likely that a user who wants a container is more knowledgeable about deployment and can resolve problems not caught by CI by themselves and/or submit an issue to GitHub, so switching off of this is fine; now, our CI will better match users who are less familiar with CD (and are likely to just use Pages out of the box).

I also will point out that `jekyll/jekyll` is **not a first-party container**, even though the namespace makes it seem like it is; it's maintained by [envygeeks](https://github.com/envygeeks/jekyll-docker). While this is very kind of them, it adds an external dependency that I would prefer to avoid.

### Build Time and `3.8.5`

This is short, but `3.8.5` isn't the latest `3` release; it's not even the latest minor patch. Since it's a "stale" container, pulling it takes a really long time (upwards of 3 minutes).

Bumping to the latest minor shouldn't affect downstream users, and has faster CI for us - which means quicker dev turnaround :) 

Node 18 has been stable for a while, so I feel comfortable making this switch; should be no downstream impact other than speed!