Responsive component

Great start Jaonary! Definitely not bad for a first challenge. Keep it up! Here are some suggestions for you:

• Avoid using pixels, especially for things like font-size, margin, padding, width, height etc. Reason being is that they don't scale with your browser's font size setting. To verify this, try increasing your browser's font size from 16px to something like 20px and do a comparison between your solution and this site. See how in your solution nothing changes, while in frontendmentor the page sort of zooms in a bit? There will be special occasions where this won't matter, but as a general advice I will suggest that you look into rems and ems.
• Decorative images that don't add anything to the page content can have an empty alt text as per the W3C Web Accessibility Initiative:

• A very small detail but I'd add a cursor: pointer to the "Proceed to payment" button to give the feedback that it's clickable.

That's all I have. Good luck to you!