Add button example to TMIL 2025-04-04 (#102)

Co-authored-by: Daniel McNab <36049421+DJMcNab@users.noreply.github.com>

Author: PoignardAzur

content/blog/2025-04-04-tmil-15/index.md

@@ -22,11 +22,18 @@ However, this was put on hold whilst the Properties experiment we mentioned last
 - [xilem#873][]: Implements properties, which is additional data attached to each widget in a uniform way, intended to enable styling.
 - [xilem#892][]: Uses properties for styling the built-in `Button` widget.
 
-<!-- TODO: Screenshot of new capability from button styling. Deferred to Olivier. Non-blocking -->
+<figure>
+<img style="height: auto" src="styled-button.png" alt="A button with a red border, a red font, and placeholder text." width="200" height="80">
+<figcaption>
+
+An example of a styled button.
+
+</figcaption>
+</figure>
 
 We have also made significant progress outside of these highlighted areas:
 
-- [xilem#897][]: Reduced the size of many of our screenshot tests, to better.
+- [xilem#897][]: Reduced the size of many of our screenshot tests.
 - [xilem#904][]: Implemented a new algorithm for screenshot testing, which better reflects the aspects of the screenshots we wish to test.
   It also implements automatic compression of blessed screenshots using the excellent [oxipng][] library.
 - [xilem#899][]: Added documentation for lots of items and methods which were missing documentation.