Removed '**Animated progress bars don't work in Opera 12**—as they don't support CSS3 animations.' note.

Bootstrap 4 doesn't (and doesn't need to) support the ancient Opera 12 released in 2012 with a 0.04% marketshare so no need to mention.

Convert them to 8-bit and compress them with optipng and zopflipng.

Before: 902 KB (923,969 bytes)
After:  431 KB (441,372 bytes)

* Prevent print utils from overriding all other display utils

Fixes #25221.

I agree with the referenced issue—this is unexpected and also causes a serious bug when mixed with other utility classes. This wasn't an issue in v3 given we had different utilities for hiding that weren't focused on display property.

* Add printing changes to migration docs

* unrelated heading sentence case change

* List out all .d-print- classes

When changing `$input-border-width`, `$input-height-border` does not change and `select.form-control` `custom-select` `custom-file` will still have `$input-height` which is resolved from `$input-btn-border-width`

This will work in cases when want controls with border, and buttons without.

Temporary fix will be to override 2 variables

```
$input-border-width: 2px !default;

// which is
// $input-height-border: $input-btn-border-width * 2 !default;
$input-height-border: $input-border-width * 2 !default;
```

* Add order-*-last grid class

* copy updates

Closes #25231

Merge branch 'form-check-input-validation' of https://github.com/supergibbs/bootstrap into supergibbs-form-check-input-validation

Closes https://github.com/twbs/bootstrap/issues/25316

* Update copyright range to include 2018

* Extend copyright date range on new files from 2017 to include 2018

* Make dropright snippet the same as demo

* Add missing .dropdown-toggle-split class

* Make clear the split button label the same as demo

* heading for better linking

* tell folks where to start

* more headings

* required keys section added, closes #25293

* fix cover nav

* Improve signin visuals and alignment with that flexbox love

* rewrite cover example in flexbox

* lighten signin bg

* first pass at pricing example

* redo examples index with data file

* tighten up spacing a bit

* update navbar descriptions

* link pricing

* move that back

* property order

* Fix test errors.

* Compress pricing.png.

* add form validation example

* remove that

* rename that

* restyle and space out

* fix errors

* change order

* cleanup album css and styles

* tweak examples index

* make it a badge

* options

* improve sticky footer alignment

* redesign example index

* brand new blog layout

* start new screenshots

* new product example page a la apple

* add email field

* fix linter, remove unused blog css

* hook up feather icons to start

* redo dashboard

* fix linting

* add floating labels example

* formatting

* formatting

* lint

* fix values on select

* optional input, plus input group

* new dashboard image

* start to reboot the offcanvas example

* updated images

* new offcanvas mostly implemented

* linting

* edit description

* more description changes

* - Add vertical margin to album hero buttons for when they're stacked
- Adjust font-size and padding for pricing header and hero
- Fix checkout's stacked column margins, plus update their check/radio
markup
- Update product's utilities to be responsive
- Made blog cards somewhat responsive (needs a bit more work tbh)

* drop leading zero

* more linting

* swap empty images for holder, fix border

* dist the docs

* navbars have no margin-bottom to begin

* add css var, tweak padding for mobile

* comment headers

* nix commented out code

* nix the navbar structure for a custom one, stack it on mobile

* tweak heading button group for mobile

* Removed narrow jumbotron and justified nav examples as these are easily accomplished with new components in v4

* improve card sizing on pricing

* update and compress

fixes #25288

* Use `$component-active-bg`, `$component-active-color` in custom-control-indicators and pagination for checked, indeterminate, and active states

* Button and Forms focus colors should be based on `$component-active-bg`

When using the `media-breakpoint-between` or `media-breakpoint-only`
mixins with a custom breakpoint map – not defined as `$grid-breakpoints`
– the mixin incorrectly defaults back to the global `$grid-breakpoints`
map in certain situations. This commit correctly passes on the
`$breakpoints` argument to the other mixins called within the block.