* Revert "Fix some icon names changed by the Font Awesome 5. (#8796)"

This reverts commit 3f9ec3de82.

* Revert "Migrate to font-awesome 5.0. (#8799)"

This reverts commit 8bae14591b.

* Revert "Fix some icons names, unavailable in fontawesome5 (free license). (#8792)"

This reverts commit b9c727a945.

* Revert "Update the icon name changed by the Font Awesome 5. (#8776)"

This reverts commit 17af4d27da.

* Revert "Add bot icon to bot avatars and migrate to newer version of Font Awesome (#8484)"

This reverts commit 4b794e134d.

This will allow easier customization of font family instead of going
through all occurrences of 'mastodon-font-sans-serif'.

Follow-up to #8142

* Add variables for text colors

* Change variables in sass files

* Apply text color variables for recently added colors

* Fix text colors of emoji mart anchors

* Fix text colors of search__input

* Fix text colors of text area of compose-form

* Fix icon colors of privacy dropdown and modal

* Inverted icon colors by classname

* Change variables in boost.scss

* Change action-button-color

* Fix text colors of pre-header

* Adjust privacy policy to be more specific to Mastodon

Fix #6613

* Change data retention of IP addresses from 5 years to 1 year

* Add even more information

* Remove all (now invalid) translations of the privacy policy

* Add information about archive takeout, remove pointless consent section

* Emphasis on DM privacy

* Improve wording

* Add line about data use for moderation purposes

* Improve styling of closed registrations message, rename button

"Sign up on another server"

Fix #6683

* Adjust styling of closed registrations message

* Use grid layout for the landing page

* Use grid layout for tag pages

* Set 2 columns width as explicit percentage for tag pages

* Use grid layout for the landing page

* Fix column settings

Set the ratio explicitly

* Improve information board

* Redesign landing page (again)

* Move login form in small version to the right column

* Display closed registrations message

* Add site setting for the hero image

* Fix test

* Increase spacing, maximum width, change call to action section

Also apply to Japanese and Korean.
Fix font-weight in landing pages.

* Fix font-weight for CJK fonts

* Use `font-weight: 700;` for mobile support

* Fix indentation

* Remove trailing whitespace

* Remove trailing whitespace

* Rename application.scss

* Move to 'default' directory

* Follow review

Move directory, and Rename "mastodon".

* Revert rename

* undo removal of newline

* Adjust landing pages 2

Fix styles of terms page
Remove action buttons from timeline in about page
Adjust styles of short description
Adjust form inputs
Set autocomplete off for username and email box in registration form. Remove line breakings.

* Revert removing action buttons

* Adjust about.scss

* Delete trailing whitespace.

* Increase contrast in about and about/more page

* Lighten em color in landing pages

* Increase contrast in landing pages


Fix about.scss

flex-basis: 0 allows make flexbox smaller than its contents on Safari <10.

https://github.com/philipwalton/flexbugs#1-minimum-content-sizing-of-flex-items-not-honored

apply same style class to the About description on both the landing page
and the about/more page

Empty a element is created when there is no business e-mail input.

* Set contact address as mailto link

To be able to copy long email address

* Set style for mailto link

* Use a fainted text color for <hr> elements in the landing page

* remove trailing whitespace

* Fix protruded infomation board section

Set "flexwrap: wrap" for sections. Set upper and lower padding for each section, and adjust clearances around sections accordingly. Settings for viewport threshold 500px is no more needed.

* Fix mistake of reducing information-board padding

In according with this fix, additional padding setting  for maximum 840px width is no more needed.

`height: 100%` in `align-self: stretch` flexboxes doesn't work on Safari < 11.

https://bugs.webkit.org/show_bug.cgi?id=137730

This workaround uses flexbox instead of `height: 100%` to stretch height.

* Fix padding in hero container, landing page

Erase hero container padding to fit registration form to full width. By this setting, heading padding disappears, so I adjust heading padding.

* Specify attribute strictly for heading padding

To overwrite padding-bottom in superior settings.

* Make padding shorthand more concise

* Adjust mobile landing page

Change mobile viewport threshold to 840px in consideration of padding. Fix loss of "container hero" padding in about/more under 675px.

* Fix indent

* Allow longer link text on landing page (reduce padding for Mobile)

* remove empty line

Setting only padding-left made the logo left-shifted on mobile page. Margin-right was old setting for adjusting clearance between old logo and letter "Mastodon".

* Redesign extended information page

* Remove unused keys

* Add $ui-base-lighter-color variable to SCSS

* Add new logo

* Remove unused images

* Redesign the landing page, mount public timeline on it

* Adjust the standalone mounted component to the lacking of router

* Adjust auth layout pages to new design

* Fix tests

* Standalone public timeline polling every 5 seconds

* Remove now obsolete translations

* Add responsive design for new landing page

* Address reviews

* Add floating clouds behind frontpage form

* Use access token from public page when available

* Fix mentions and hashtags links, cursor on status content in standalone mode

* Add footer link to source code

* Fix errors on pages that don't embed the component, use classnames

* Fix tests

* Change anonymous autoPlayGif default to false

* When gif autoplay is disabled, hover to play

* Add option to hide the timeline preview

* Slightly improve alt layout

* Add elephant friend to new frontpage

* Display "back to mastodon" in place of "login" when logged in on frontpage

* Change polling time to 3s

- Updates scss variables file to use better-named variables for black/white/etc
- Arranges the "mastodon classic" colors into variables
- Remove all references to `$color-*` naming, replacing with new

This does not in itself introduce "theme" support, but:

- It would probably be easier to start working on theme support after this
  change and others
- Even without the goal of themes, these changes make it more clear how the
  colors are being used.

There is almost definitely some edge case in here where I've guessed the
intent/context of some color usage incorrectly, but it still seems like a net
improvement.

* add scss_lint to Gemfile

* add .scss-lint.yml

* fix warnings of scss-lint

* chmod -x styles/variables.scss

* Enable CodeClimate SCSS Lint checks

* Fix local fonts and change font-face values

* Remove eot font files