CSS Animations: Learning to create smooth and visually appealing animations using CSS was a challenge. I had to experiment with different properties and values to achieve the desired effects.

Browser Compatibility: Ensuring that the CSS worked consistently across different browsers was tricky. Some animations looked great in one browser but not in another.

Responsive Design: Making sure the buttons looked good on various screen sizes required careful adjustments and media queries.

Debugging: Finding and fixing errors in the CSS was time-consuming. Missing semicolons and incorrect property values were common issues.

Button Interactivity: Adding interactive effects like hover and active states involved understanding CSS transitions and keyframes.