QR Code Component

Some recommendations regarding your code that could be of interest to you.

HTML

• In order to fix the accessibility issues, you need to replace <div class="main"> with the <main> tag. :) You'd better use Semantic HTML, and you can also reach more information about it from Semantic HTML and Using Semantic HTML Tags Correctly.

• Also each main content needs to start with an h1 element, and also contain only one h1 element. Your accessibility report states the need for one main landmark. So, you need to use a <h1> element in the <main> tag instead of using the <h2> element. You can replace the <h2>Improve your front-end skills by building projects</h2> element with the <h1>Improve your front-end skills by building projects</h1> element.

CSS

• If you want to center it correctly, you can add these styles:

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

Hope I am helpful. :)