Steam Achievement Notifier lets you customize the look of Steam achievement notifications and choose a design that suits your taste.
When you earn an achievement in Steam, a corresponding notification pops up on your desktop. I find it a bit ugly, and it appears in some corner of the screen.
If you’re not a fan of the default notification design either, you can easily tweak it using the Steam Achievement Notifier app.
By default there are three display themes: Main, Rare, and 100%. However, when you click the Customise button, you can adjust every aspect of the notification’s appearance. On the left panel you can preview your changes before applying them.
Once you’ve finished customizing, the next time you earn an achievement in a game, your personalized notification will appear to celebrate the moment.