Add new docsref page, fix docs border-radius issues (#38491)

* Add new docsref page, fix docs border-radius issues

* Remove commented out code

* Update docsref.md

* Fix no-code example, fix mobile styles

* Updates from review

* Fix block margin, remove margin-right from pre on mobile since no clipboard icons, adjust masthead snippet

* Fix errant styles for border-radius on homepage

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Co-authored-by: XhmikosR <xhmikosr@gmail.com>

site/content/docs/5.3/docsref.md

@@ -0,0 +1,49 @@
+---
+layout: docs
+title: Docs reference
+description: Examples of Bootstrap's documentation-specific components and styles.
+aliases: "/docsref/"
+toc: true
+robots: noindex,follow
+sitemap_exclude: true
+---
+
+## Buttons
+
+<button class="btn btn-bd-primary">Primary button</button>
+<button class="btn btn-bd-accent">Accent button</button>
+<button class="btn btn-bd-light">Light button</button>
+
+## Callouts
+
+{{< callout >}}
+  Default callout
+{{< /callout >}}
+
+{{< callout warning >}}
+  Warning callout
+{{< /callout >}}
+
+{{< callout danger >}}
+  Danger callout
+{{< /callout >}}
+
+## Code example
+
+```scss
+.test {
+  --color: blue;
+}
+```
+
+<div class="bd-example">
+  The <abbr title="HyperText Markup Language">HTML</abbr> abbreviation element.
+</div>
+
+{{< example >}}
+<div class="test">This is a test.</div>
+{{< /example >}}
+
+{{< scss-docs name="variable-gradient" file="scss/_variables.scss" >}}
+
+{{< js-docs name="live-toast" file="site/assets/js/snippets.js" >}}