docs: switch to fenced codeblocks (#31806)

site/content/docs/5.0/helpers/clearfix.md

@@ -10,9 +10,9 @@ Easily clear `float`s by adding `.clearfix` **to the parent element**. Can also
 
 Use in HTML:
 
-{{< highlight html >}}
+```html
 <div class="clearfix">...</div>
-{{< /highlight >}}
+```
 
 The mixin source code:
 
@@ -20,11 +20,11 @@ The mixin source code:
 
 Use the mixin in SCSS:
 
-{{< highlight scss >}}
+```scss
 .element {
   @include clearfix;
 }
-{{< /highlight >}}
+```
 
 The following example shows how the clearfix can be used. Without the clearfix the wrapping div would not span around the buttons which would cause a broken layout.
 

site/content/docs/5.0/helpers/position.md

@@ -10,33 +10,33 @@ toc: true
 
 Position an element at the top of the viewport, from edge to edge. Be sure you understand the ramifications of fixed position in your project; you may need to add additional CSS.
 
-{{< highlight html >}}
+```html
 <div class="fixed-top">...</div>
-{{< /highlight >}}
+```
 
 ## Fixed bottom
 
 Position an element at the bottom of the viewport, from edge to edge. Be sure you understand the ramifications of fixed position in your project; you may need to add additional CSS.
 
-{{< highlight html >}}
+```html
 <div class="fixed-bottom">...</div>
-{{< /highlight >}}
+```
 
 ## Sticky top
 
 Position an element at the top of the viewport, from edge to edge, but only after you scroll past it. The `.sticky-top` utility uses CSS's `position: sticky`, which isn't fully supported in all browsers.
 
-{{< highlight html >}}
+```html
 <div class="sticky-top">...</div>
-{{< /highlight >}}
+```
 
 ## Responsive sticky top
 
 Responsive variations also exist for `.sticky-top` utility.
 
-{{< highlight html >}}
+```html
 <div class="sticky-sm-top">Stick to the top on viewports sized SM (small) or wider</div>
 <div class="sticky-md-top">Stick to the top on viewports sized MD (medium) or wider</div>
 <div class="sticky-lg-top">Stick to the top on viewports sized LG (large) or wider</div>
 <div class="sticky-xl-top">Stick to the top on viewports sized XL (extra-large) or wider</div>
-{{< /highlight >}}
+```

site/content/docs/5.0/helpers/ratio.md

@@ -59,13 +59,13 @@ For example, to create a 2x1 aspect ratio, set `--aspect-ratio: 50%` on the `.ra
 
 This CSS variable makes it easy to modify the aspect ratio across breakpoints. The following is 4x3 to start, but changes to a custom 2x1 at the medium breakpoint.
 
-{{< highlight scss >}}
+```scss
 .ratio-4x3 {
   @include media-breakpoint-up(md) {
     --aspect-ratio: 50%; // 2x1
   }
 }
-{{< /highlight >}}
+```
 
 {{< example class="bd-example-ratios bd-example-ratios-breakpoint" >}}
 <div class="ratio ratio-4x3">

site/content/docs/5.0/helpers/visually-hidden.md

@@ -13,7 +13,7 @@ Visually hide an element while still allowing it to be exposed to assistive tech
 <a class="visually-hidden-focusable" href="#content">Skip to main content</a>
 {{< /example >}}
 
-{{< highlight scss >}}
+```scss
 // Usage as a mixin
 
 .visually-hidden-title {
@@ -23,4 +23,4 @@ Visually hide an element while still allowing it to be exposed to assistive tech
 .skip-navigation {
   @include visually-hidden-focusable;
 }
-{{< /highlight >}}
+```