Rework progress bar markup and styles (#36831)

* Rework progress bar markup and styles

Logically moves the various `role` and `aria-` attributes to the `.progress` element itself, leaving the `.progress-bar` to be used purely for the visual presentation. This fixes the problem #36736 that in certain browser/AT combinations, zero-value/zero-width progress bars are completely ignored and not announced.

For multiple/stacked progress bars, this PR introduces a new wrapper and class `.progress-stacked`, to accommodate for the fact that with the more logical structure above, we need full `.progress` elements with child `.progress-bar` elements, and can't get away with the fudge we had before of having a single `.progress` with multiple `.progress-bar`s.

Note that the old markup structures still work with this change, so this could be considered a non-breaking change - though one we definitely want to highlight as it's more accessible (as it now guarantees that zero-value/zero-width progress bars, whether on their own or as part of a multi/stacked bar, are actually announced)

* Add a note about progress bar change in migration guide

* Add notes with old markup examples and explanation

* Fix bundlewatch

* Update site/content/docs/5.2/components/progress.md

Co-authored-by: Julien Déramond <[email protected]>

* Reintroduce deleted styles

Turns out they're needed for correct positioning of text inside progress bar

* Move changes in markup to Migrationg guide, link to that from top of progress page, rewrite some content

* Fix typo in callout

* Clarify "Sizing" section

* Remove redundant "now"

Co-authored-by: Julien Déramond <[email protected]>
Co-authored-by: Julien Déramond <[email protected]>
Co-authored-by: Mark Otto <[email protected]>
Co-authored-by: Mark Otto <[email protected]>

1 files changed, 10 insertions, 1 deletions

diff --git a/scss/_progress.scss b/scss/_progress.scss
index 1bfafb58f..148c3815e 100644
--- a/scss/_progress.scss
+++ b/scss/_progress.scss
@@ -8,7 +8,8 @@
 }
 // scss-docs-end progress-keyframes
 
-.progress {
+.progress,
+.progress-stacked {
   // scss-docs-start progress-css-vars
   --#{$prefix}progress-height: #{$progress-height};
   @include rfs($progress-font-size, --#{$prefix}progress-font-size);
@@ -46,6 +47,14 @@
   background-size: var(--#{$prefix}progress-height) var(--#{$prefix}progress-height);
 }
 
+.progress-stacked > .progress {
+  overflow: visible;
+}
+
+.progress-stacked > .progress > .progress-bar {
+  width: 100%;
+}
+
 @if $enable-transitions {
   .progress-bar-animated {
     animation: $progress-bar-animation-timing progress-bar-stripes;