componente de código QR HTML ad CSS

Hello! Your solution looks really good! 😁

Here is some advice:

• you shoud do a reset in css, read about that here -> CSS reset, to do that add in your CSS file:

* { 
     margin: 0;
     padding: 0;
     box-sizing: border-box;
}

• also I recomend you to use semantic tags, learn about it here -> sematic tags,
• to center the card, add these styles:

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

Hope it was helpful and happy coding 😃