Browsers introduce a opaque background on iframes if the iframe
element's color-scheme does not match the document's color scheme which
in case of a dark theme results in a mismatch and the browser adds a
white background. Avoid this by specifying the same color scheme outside
and inside the iframe.

See https://fvsch.com/transparent-iframes for more info.

My initial attempt was to make the iframe document the same color-scheme
as the parent page (light or dark) but with that, there was a ugly
background flash on load in Chrome because Chrome apparently always
loads iframe in light scheme initially. Firefox still shows a background
flash on load but this is not possible to get rid of and it's certainly
a browser bug.

Before:
<img width="1147" alt="Screen Shot 2022-10-31 at 13 30 55"
src="https://user-images.githubusercontent.com/115237/199017132-9828aace-bdd0-4ede-8118-359e72bcf2fe.png">

After:
<img width="1152" alt="Screen Shot 2022-10-31 at 13 30 36"
src="https://user-images.githubusercontent.com/115237/199017137-989a9e67-3fe0-445f-a191-df5bf290dabf.png">

Remove remaining non-color variables in arc-green, so the theme is now
100% defined from variables (excluding inverts). Adjusted red/green to
match previous overwritten colors.

`--color-gold-light` is removed, it was unused and is not part of
fomantic colors.

<img width="772" alt="Screen Shot 2022-10-24 at 20 22 25"
src="https://user-images.githubusercontent.com/115237/197599339-1d1bf6e3-aa90-4f38-9753-24effd4b178d.png">
<img width="275" alt="Screen Shot 2022-10-24 at 20 25 52"
src="https://user-images.githubusercontent.com/115237/197599344-79c1d3ac-c709-4e30-a60b-4738af672c12.png">
<img width="446" alt="Screen Shot 2022-10-24 at 20 26 46"
src="https://user-images.githubusercontent.com/115237/197599346-f2ef6449-7efd-4f81-bbb6-e7bee4528f50.png">

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Introduce a CSS class `.unselectable`

* Various Mermaid improvments

- Render into iframe for improved security
- Use built-in dark theme instead of color inversion
- Remove flexbox attributes, resulting in more consistent size rendering
- Update API usage and update to latest version

* restart ci

* misc tweaks

* remove unneccesary declaration

* make it work without allow-same-origin, add loading=lazy

* remove loading attribute, does not seem to work

* rename variable

* skip roundtrip to DOM for rendering

* don't guess chart height

* update comment to make it clear it's intentional

* tweak

* replace deprecated 'scrolling' property

* remove unused css file

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

* Bug fix: render Markdown http://AppURL/org/repo/issues/4?a=1&b=2#comment-123 test to HTML correctly, close #17394
* Bug fix: fix the positions of checkboxes in rendered HTML, close #17395

this forces browsers to render background correctly

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

* creates and implements generic markup less class

* How to give custom CSS to externally rendered html

* Clarifies sources of CSS styling of markup

* further clarification of sources of markup styling

* rename _markdown to _markup

* remove defunct import

* fix orphaned reference

* Update docs/content/doc/advanced/external-renderers.en-us.md

* more renames markdown -> markup

* do not suggest less customization

* add back tokens

* fix class whitespace, remove useless if-clause

* remove unused csv-data rules

* use named exports and rename functions

* sort imports

Co-authored-by: HarvsG <11440490+HarvsG@users.noreply.github.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: silverwind <me@silverwind.io>

Update Markdown CSS to more closely match GH rendering. Changes include
better nested list margins and tweaked font sizes.

Co-authored-by: Lauris BH <lauris@nix.lv>

Implements request #14320 The rendering of CSV files does match the diff style.

* Moved CSV logic into base package.

* Added method to create a tabular diff.

* Added CSV compare context.

* Added CSV diff template.

* Use new table style in CSV markup.

* Added file size limit for CSV rendering.

* Display CSV parser errors in diff.

* Lazy read single file.

* Lazy read rows for full diff.

* Added unit tests for various CSV changes.

Blink still requires a vendor prefix for `mask-image` and `mask-size`,
so add that here to fix the rendering.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

* Markdown task list improvements

- Remove `.ui` class and wrappers to prevent fomantic from messing with it.
- Change rendered HTML to match GitHub.
- Add custom styling for the checkboxes.

* fix unittest

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

- Enable wrapping of long lines in code blocks like already done in code
  view.
- Slightly lighten the background of code blocks on default theme
- Darken the background on inline code and kbd elements on arc-green

Co-authored-by: 6543 <6543@obermui.de>

* Markdown and Repo header tweaks

- Use CSS vars for all markdown colors
- Tweak repo header, removing double borders and adjust sizes
- Use menu instead of buttons for issue open/close switcher
- Add emoji inversion for select emoji glyphs in arc-green
- Use border over box-shadow for all buttons
- Add spacing element to login form without openid

* repo settings navbar fix

* use shared template in more places and adjust dashboard

* fix remaining open/close combos

Previously it was reduced globally from 700 to 500 but it actually needs
to be 600 to match GitHub's rendering.

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: zeripath <art27@cantab.net>

* CSS color variables, less bold font weight

- Define color variables for fully saturated colors and apply them where
  it made sense
- Add background color helper classes
- Globally reduce bold font weight from 700 to 500
- Remove border from timeline icons
- Unify dropzone styling
- Various border style consolidations

* attempt to fix test

* another attempt at tests

* fix contains

- Convert all tooltips to JS-based ones, fixing overflow issues
- Restyle issue dependencies/dependants
- Move popup styles to base style
- CSS Helper tweaks
- Unify pseudo element selectors and lint for it

Fixes: https://github.com/go-gitea/gitea/issues/13400

Reindent and unify codebase to 2-space indentation.

- Add loading spinners on editor and mermaid renderers
- Add error handling and inline error box for mermaid
- Fix Mermaid rendering by using the .init api

* Add mermaid JS renderer

For feature parity with GitLab. Tested in files, issues, wiki, editor.
arc-green only does an inversion because the renderer seems to like to
render white backgrounds on boxes.

Ref: https://github.com/go-gitea/gitea/issues/3340
Fixes: https://github.com/go-gitea/gitea/issues/12307

* add feature entry, switch to neutral theme, remove border

* add bindFunctions support

* remove unnecessary border-radius

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

This changes the links on headings like '# Usage' in markdown from

  `https://host/user/repo#user-content-usage`

to just

  `https://host/user/repo#usage`

matching GitHub and GitLab. The linked id elements still have the prefix
and this behaviour matches GitHub and GitLab too, so JS is needed to
scroll to the active anchor. I suspect it's like that to avoid namespace
collission between user-generated content and other page content.
Compatibilty for old links is included so they will continue to work.

Also included are some enhancements to make the clickable area for the
link icon larger and fix its color on arc-green.

Fixes: https://github.com/go-gitea/gitea/issues/11896
Fixes: https://github.com/go-gitea/gitea/issues/12062

Enabled the rule and --fix'ed issues.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Fix #11317

Signed-off-by: Andrew Thornton <art27@cantab.net>

- remove whitespace before and after
- increase horizontal padding
- make blocks more apparant on arc-green

* Fix task-list checkbox styling

The pandoc renderer will append the class "task-list" to the ul element
wrapping a li with one or more check-boxes. This allows us to select for
them, removing their list-style-type property. However, goldmark and the
gfm spec doesn't specify the "task-list" class name, so we can't use
that to fix the issue there.

Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>

* Update to goldmark v1.1.25

This version adds the missing space after a checkbox.

Resolves: #9656

Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>

Co-authored-by: zeripath <art27@cantab.net>

* add history comments to detect page delete

Signed-off-by: Michael Gnehr <michael@gnehr.de>

* fix too much history entries
- caused by --follow flag
  - if files with same contents exists

Signed-off-by: Michael Gnehr <michael@gnehr.de>

* style imprevements wiki
- history - wrap long author names

Signed-off-by: Michael Gnehr <michael@gnehr.de>

fix #7

* add wiki page revision list

* mobile improvements

* css improvements for long usernames

* split renderWikiPage into 3 functions

Signed-off-by: Michael Gnehr <michael@gnehr.de>

New CSS linter which is much more powerfull than the previous one.
Configuration is default but I had to remove a few rules that were
throwing too many or weird errors.

More importantly, the linter will exit with code 1 on errors so now our
build will fail if the CSS linter fails which should eliminate linter
errors being introduced without notice.

* Add lang specific font stacks

* Force font changes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix icons

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix octicons and icons

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Just override the semantic ui fonts only

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Missed the headers... override them too

* Missed some more semantic ui stuff

* Fix PT Sans

Signed-off-by: Andrew Thornton <art27@cantab.net>

* More changes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Squashed commit of the following:

commit 7d1679e907
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 13:53:49 2019 +0100

    Remove missed YaHei leftover from _home.less

commit 0079121ea9
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 12:03:54 2019 +0100

    Fix overdone fixes (inherit, :lang)

commit 62c9199159
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 02:29:10 2019 +0100

    Fix elements w/ explicit lang (language chooser)

commit b3117587aa
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 20:17:26 2019 +0100

    Fix textarea also (to match body)

commit 81cedf2c30
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 19:41:39 2019 +0100

    Revert css temporarily to fix conflict

commit 80ff82797f
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 19:15:30 2019 +0100

    Tweak CJK, fix Yu Gothic, more monospace inherits

commit 581dceb9a8
Author: Mike L <cl.jeremy@qq.com>
Date:   Mon Mar 11 13:09:26 2019 +0100

    Add Lato for latin extd. & cyrillic, improve CJK

* update stylesheet

* Allow markdown table to scroll

`overflow:auto` isn't effective when a table is wider than the container. Adding `display:block` fixes this issue.

Signed-off-by: Andrew Boyarshin <andrew.boyarshin@gmail.com>

* Markdown rendering overhaul

Cleaned up and squashed commits into single one.

Signed-off-by: Andrew Boyarshin <boyarshinand@gmail.com>

* Fix markdown API, add markdown module and API tests, improve code coverage

Signed-off-by: Andrew Boyarshin <boyarshinand@gmail.com>

This does not change any content and generated gogs.css is still the same.

- copy link button: #1396, #1168, #1668,
- synxtax highlight: #1712, #1549, #1315, #670
- z-index: #1942

- conf/locale: add mew translator profile