3-column-preview-card-component using HTML, CSS and Flexbox

well the first main thing to address is the size of your mobile layout. You might want to check your size on your container class in mobile view it is 940px wide when I removed that it helped things. But not sure if you did this challenge mobile first or desktop first. It might be good to start this challenge again mobile first and take what you have learned and reinforce you learning trying to improve on what you have done so far

also you need to check your border radius on your cards

Hi there, Lucas Henrique dos Santos! 👋

Congratulations on completing your first Frontend Mentor challenge! 🎉 Good effort on this one! 👍

Like palgramming mentioned, it would be worth taking another look at the responsiveness of your site. You could switch to a mobile-friendly layout for the card component sooner (to avoid having a horizontal scroll bar appear along the bottom of the page) and allow the width of the card in the mobile layout to be determined by the size of the screen (so that it all fits within the viewport for users to see).

And also, it would be better to add border-radius to the card container itself (not the individual sections of the card) so that the rounded corners are only seen at the edges of the entire card component. 😉

Keep coding (and happy coding, too)! 😁