* Add .dropdown-item-text class

* Add example of plain text within a .dropdown-menu, too

* reorganize, simple/clearer headings

Opera 19 was released in January 2014 and auto-updates so I suggest no need to mention about browser support for this old version.

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.

* Make dropright snippet the same as demo

* Add missing .dropdown-toggle-split class

* Make clear the split button label the same as demo

fixes #25288

* Add additional form validation examples

Fixes #24811.

This adds .valid-feedback to our custom styles and server side examples; previously we ommitted this to suggest you don't always need valid feedback. In addition, this adds examples of the .{valid|invalid}-tooltip classes with a new subsection in the Validation docs.

* Update validation tooltip styles to remove fixed width; instead should retain itself to the parent element

* update ids

* finish docs paragraph, mention position: relative

* Remove incorrect roles from accordion, tweak/expand accessibility info
* Use `<button>` elements rather than links for the accordion

This commit allows nested structures for accordions. Also a part of
the documentation about data-children is removed because this
functionality didn't work and it's not applicable anymore.

Tests with the collapse accordion are also a bit adjusted to the new
situation.

"Choose file ..." text is now written inside the label tag, so the translation is outside the css scope. 
$custom-file-text variable should only contain "Browse" translations.

Closes #25067

- Changes the wrapping label to a div so we can style the label instead of another element while also supporting form validation.
- Fixes form validation styles for custom file input (closes #24831).
- Updates docs with validation styles (also adding example feedback text while I was there) and new how it works section.

Adds some additional context on `.form-group` usage

* Restyle code element, clean up variables

- Removes the padding and background-color
- Changes the color to a brand color ()
- Add new variables to kbd element styles to account for removing the code ones
- Remove overrides that were needed previously

* only break between words, and override it in the pre

* make file inputs 100% wide

* scope custom file changes in input group for sizing

* shorter button labels for responsive

* narrower cards

* button was too wide

* downsize

* fewer links in pagination

* redo cell text

* improve overflow docs

* match layout behaviors

* ditch the indicator as separate element for psuedo-elements on the label

* move disabled to attribute only on input

* redo default inline check to support new markup

* redo inline forms

* clean up vars

* update validation mixin to new structure

* update checks in docs

* linting for for/id attributes

* Rewrite input group component

* Set the feedback to 100% width for input group

* Move from .row to .form-row for tighter layout

* no need for custom feedback here, we're using browser messaging

* add input group to validation examples

* add note about validating multiple

* migration note added

* chore: sync with twbs (#1)

* Make styling of grouped option buttons class-based

Referencing #23728, styling grouped radio and checkbox buttons should not require the data-toggle attribute.

* Fix installing deps in our webpack docs

* Fix nested cards on card group (#24766)

* Update popper.js to v1.12.9. (#24797)

* Don't run postcss for `dist/css/*.min.css` files. (#24676)

* Change the text color to dark on bg color warning examples (#24805)

* Remove unused file and bundle ie-emulation-modes-warning.js with docs.min.js (#24825)

* Remove the unused assets/js/ie10-viewport-bug-workaround.js.

* Combine ie-emulation-modes-warning.js with docs.min.js.

* Typos in grid.md (#24828)

Fixed typos in offsetting section of grid.md

* Fix dropup example code

* Update devDependencies. (#24829)

* Add support for fractional viewport widths (zoom/high-dpi displays) (#24299)

* Change breakpoint  max- calculation to fractional values
* Update docs to reflect fractional max-width breakpoint values
* Add fractional max-width to offcanvas example
* Add documentation and SCSS comment for fractional viewport support

* Add a simple script to generate SRI hashes for our assets. (#24814)

* Allow us to run our unit test on differents jquery version

* Run karma tests in parallel.

* Update typography docs (#24863)

* closes #24450

* Rewrite custom form check backgrounds (#24697)

* Rewrite custom form check backgrounds

Previously, this was all just a background-color and background-image. When we restored the gradients though, we had two background-images competing on the same element, causing rendering glitches. This refactors that code, creating a mixin to simplify things, so we can we easily use two background-images (SVG icon and gradient) when -gradients is set to true.

Fixes #24598

* restore default vars

* Revamp custom check and radio backgrounds

Instead of applying multiple background-image's to the same element, we're adding a new ::before pseudo-element to layer the background-images. Gradients go on the .custom-control-indicator while their icons go on the ::before element. This allows us to shave some bytes from when we compile and we previously needed to redeclare the background-image for the icon if you changed the gradient.

* remove now unused mixin

* mention change in migration docs

* lets the centered modal have any height (#24803)

* Custom select updates (#24699)

* Add support for size attribute on custom selects

* Add large custom select, document it and the small variant

* fix custom select focus state

* fix custom file input focus styles

* remove empty line

* Update package.json. (#24582)

1. Use the same jQuery version in jspm
2. Update the files to only include the source and dist folders

* Use Jekyll's `smartify` filter when possible. (#24866)

* Darken outline hover color to match default button hover (#24150)

* Fix Issue #24144

Alter button-outline-variant mixin to darken hover and active background in same fashion as filled button.

* Fix Issue #24144

Filled button on hover should utilize the same color-yiq mixin so that theme buttons match

* default values, fix mixin

* rename it

* document it

* add migration note

* fixes #24728

* Remove unused CSS. (#24872)

* tab.js: do not remove fade class if there's no initial active pane

* Restore currently unused variables (#24891)

* Replace lint-vars.sh with a Node.js script. (#24860)

Also, include it in the `css` npm script since it's instant.

* Fix docs horizontal scrollbar (#24878)

* Fix docs horizontal scrollbar in Components > Modal

* Add overflow to docs example class

* Drop the handleUpdate() variant

While I understand the variant covers the "get a particular plugin instance" case from http://getbootstrap.com/docs/4.0/getting-started/javascript/#programmatic-api it seems weird that we do it here but not everywhere else in the docs (randomly checking other pages, we seem to stick to the documented methods as written on those pages). As this isn't properly explained as is, and as it adds nothing (more of a preference for authors), it would be easier to just drop the variant and stick with the documented method as outlined later on in the same page (avoids having to go off on a "why should you use this instead of that" tangent here).

* Combine path and remove variable used in one place. (#24873)

* Update devDependencies and gems. (#24876)

* Override padding on radio input label (#24899)

We could tell folks to nix the class, we could tell them to override it, or we could add another modifier of some kind to address this. None of them seem particularly useful, but the padding override feels the most approachable and clearly documentable. Added this here to close #24844.

* Update README.md (#24912)

* Work around Travis failures.

Note that we should revert this when the issue is fixed.

* Revert the Travis workaround. (#24926)

The issue has been fixed.

* add .col-form-legend-lg and .col-form-legend-sm classes

* document .col-form-legend-{size}

* trash .col-form-legend completely

One class fits all

* Update forms.md

* consolidate copy

* property order

We could tell folks to nix the class, we could tell them to override it, or we could add another modifier of some kind to address this. None of them seem particularly useful, but the padding override feels the most approachable and clearly documentable. Added this here to close #24844.