Responsive simple page using flexbox

What are you most proud of, and what would you do differently next time?

I am proud to have made a project that seems to adapt to different screen sizes.

What challenges did you encounter, and how did you overcome them?

Finally figured out why I couldn't align an element vertically to the entire page. I just had to put these lines of code to get it done:

html, body, main {
    width: 100%;
    height: 100%;
}

And then drag these lines to center the element:

.qr-code-box-container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
}

It's very simple but I really struggled with it before.

What specific areas of your project would you like help with?

Does the final result visually match what was requested ? Is the code well organized ?