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

5 files changed, 24 insertions, 12 deletions

diff --git a/_includes/callout-info-mediaqueries-breakpoints.md b/_includes/callout-info-mediaqueries-breakpoints.md
new file mode 100644
index 000000000..ddf2b3745
--- /dev/null
+++ b/_includes/callout-info-mediaqueries-breakpoints.md
@@ -0,0 +1,3 @@
+{% callout info %}
+Note that since browsers do not currently support [range context queries](https://www.w3.org/TR/mediaqueries-4/#range-context), we work around the limitations of [`min-` and `max-` prefixes](https://www.w3.org/TR/mediaqueries-4/#mq-min-max) and viewports with fractional widths (which can occur under certain conditions on high-dpi devices, for instance) by using values with higher precision for these comparisons.
+{% endcallout %}
\ No newline at end of file
diff --git a/docs/4.0/content/tables.md b/docs/4.0/content/tables.md
index 791de590d..0aefc9ad1 100644
--- a/docs/4.0/content/tables.md
+++ b/docs/4.0/content/tables.md
@@ -579,6 +579,10 @@ Regular table background variants are not available with the dark table, however
 {% capture callout-include %}{% include callout-warning-color-assistive-technologies.md %}{% endcapture %}
 {{ callout-include | markdownify }}
 
+Create responsive tables by adding `.table-responsive{-sm|-md|-lg|-xl}` to any `.table` to make them scroll horizontally at each `max-width` breakpoint of 575.99px, 767.99px, 991.99px, and 1119.99px, respectively.
+
+{% capture callout-include %}{% include callout-info-mediaqueries-breakpoints.md %}{% endcapture %}
+{{ callout-include | markdownify }}
 
 ## Captions
 
diff --git a/docs/4.0/examples/offcanvas/offcanvas.css b/docs/4.0/examples/offcanvas/offcanvas.css
index 1c9ca3b44..c23004ad4 100644
--- a/docs/4.0/examples/offcanvas/offcanvas.css
+++ b/docs/4.0/examples/offcanvas/offcanvas.css
@@ -17,7 +17,7 @@ footer {
  * Off Canvas
  * --------------------------------------------------
  */
-@media screen and (max-width: 767px) {
+@media screen and (max-width: 767.99px) {
   .row-offcanvas {
     position: relative;
     transition: all .25s ease-out;
diff --git a/docs/4.0/layout/overview.md b/docs/4.0/layout/overview.md
index 4952da5b7..9ac82d7bd 100644
--- a/docs/4.0/layout/overview.md
+++ b/docs/4.0/layout/overview.md
@@ -88,21 +88,24 @@ We occasionally use media queries that go in the other direction (the given scre
 
 {% highlight scss %}
 // Extra small devices (portrait phones, less than 576px)
-@media (max-width: 575px) { ... }
+@media (max-width: 575.99px) { ... }
 
 // Small devices (landscape phones, less than 768px)
-@media (max-width: 767px) { ... }
+@media (max-width: 767.99px) { ... }
 
 // Medium devices (tablets, less than 992px)
-@media (max-width: 991px) { ... }
+@media (max-width: 991.99px) { ... }
 
 // Large devices (desktops, less than 1200px)
-@media (max-width: 1199px) { ... }
+@media (max-width: 1199.99px) { ... }
 
 // Extra large devices (large desktops)
 // No media query since the extra-large breakpoint has no upper bound on its width
 {% endhighlight %}
 
+{% capture callout-include %}{% include callout-info-mediaqueries-breakpoints.md %}{% endcapture %}
+{{ callout-include | markdownify }}
+
 Once again, these media queries are also available via Sass mixins:
 
 {% highlight scss %}
@@ -116,16 +119,16 @@ There are also media queries and mixins for targeting a single segment of screen
 
 {% highlight scss %}
 // Extra small devices (portrait phones, less than 576px)
-@media (max-width: 575px) { ... }
+@media (max-width: 575.99px) { ... }
 
 // Small devices (landscape phones, 576px and up)
-@media (min-width: 576px) and (max-width: 767px) { ... }
+@media (min-width: 576px) and (max-width: 767.99px) { ... }
 
 // Medium devices (tablets, 768px and up)
-@media (min-width: 768px) and (max-width: 991px) { ... }
+@media (min-width: 768px) and (max-width: 991.99px) { ... }
 
 // Large devices (desktops, 992px and up)
-@media (min-width: 992px) and (max-width: 1199px) { ... }
+@media (min-width: 992px) and (max-width: 1199.99px) { ... }
 
 // Extra large devices (large desktops, 1200px and up)
 @media (min-width: 1200px) { ... }
@@ -146,7 +149,7 @@ Similarly, media queries may span multiple breakpoint widths:
 {% highlight scss %}
 // Example
 // Apply styles starting from medium devices and up to extra large devices
-@media (min-width: 768px) and (max-width: 1199px) { ... }
+@media (min-width: 768px) and (max-width: 1199.99px) { ... }
 {% endhighlight %}
 
 The Sass mixin for targeting the same screen size range would be:
diff --git a/scss/mixins/_breakpoints.scss b/scss/mixins/_breakpoints.scss
index a9866bd90..7c95c688f 100644
--- a/scss/mixins/_breakpoints.scss
+++ b/scss/mixins/_breakpoints.scss
@@ -29,13 +29,15 @@
 }
 
 // Maximum breakpoint width. Null for the largest (last) breakpoint.
-// The maximum value is calculated as the minimum of the next one less 0.1.
+// The maximum value is calculated as the minimum of the next one less 0.01px
+// to work around the limitations of `min-` and `max-` prefixes and viewports with fractional widths.
+// See https://www.w3.org/TR/mediaqueries-4/#mq-min-max
 //
 //    >> breakpoint-max(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
 //    767px
 @function breakpoint-max($name, $breakpoints: $grid-breakpoints) {
   $next: breakpoint-next($name, $breakpoints);
-  @return if($next, breakpoint-min($next, $breakpoints) - 1px, null);
+  @return if($next, breakpoint-min($next, $breakpoints) - .01px, null);
 }
 
 // Returns a blank string if smallest breakpoint, otherwise returns the name with a dash infront.