Adding upstream version 5.2.3+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

site/content/docs/5.2/components/close-button.md

@@ -0,0 +1,38 @@
+---
+layout: docs
+title: Close button
+description: A generic close button for dismissing content like modals and alerts.
+group: components
+toc: true
+---
+
+## Example
+
+Provide an option to dismiss or close a component with `.btn-close`. Default styling is limited, but highly customizable. Modify the Sass variables to replace the default `background-image`. **Be sure to include text for screen readers**, as we've done with `aria-label`.
+
+{{< example >}}
+<button type="button" class="btn-close" aria-label="Close"></button>
+{{< /example >}}
+
+## Disabled state
+
+Disabled close buttons change their `opacity`. We've also applied `pointer-events: none` and `user-select: none` to preventing hover and active states from triggering.
+
+{{< example >}}
+<button type="button" class="btn-close" disabled aria-label="Close"></button>
+{{< /example >}}
+
+## White variant
+
+Change the default `.btn-close` to be white with the `.btn-close-white` class. This class uses the `filter` property to invert the `background-image`.
+
+{{< example class="bg-dark" >}}
+<button type="button" class="btn-close btn-close-white" aria-label="Close"></button>
+<button type="button" class="btn-close btn-close-white" disabled aria-label="Close"></button>
+{{< /example >}}
+
+## Sass
+
+### Variables
+
+{{< scss-docs name="close-variables" file="scss/_variables.scss" >}}