Responsive QR Code Component

There is no need to give the body a min-width and max-width value rather give that to the main.

To center the main on the page, add min-height:100vh; display: flex; align-items: center: justify-content: center; or min-height:100vh; display: grid place-items: center to the body.

To center  the main on the page using flexbox:
body{
min-height: 100vh;
display: flex;
align-items: center;
justify-content: center;
}

To center  the main on the page using grid:
body{
min-height: 100vh;
display: grid;
place-items: center;
}

Give h1 and p a font-size of 15px. Give the img a max-width of 100%. Use relative units like rem or em as unit for the padding, margin, width values and preferably rem for the font-size values, instead of using px which is an absolute unit. For more on CSS units Click here

Hope am helpful.

Well done for completing this challenge. HAPPY CODING