Static QR flashcard using HTML & CSS

Replace <div id="center"> with the main tag and <p class="paragraph1"> with <h1> to fix the accessibility issues. click here for more on web-accessibility and semantic html

There is no need to give #card a height value. Give h1 and p the same font-size of 15px, the same margin-right, margin-left and marfgin-top values. Give p a margin-bottom value. There is no need to give p and h1 font-weight values.

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

You have achieved desired results with minimal amount of code. It looks good.

From design point you can reduce the drop shadow transparency. 0.05 to 0.1 would look good.

Now coming to css selectors for best practice use classes as much as possible avoid id's.

Use semantic elements. In your case <div> tag with id name center, replace it with <main> tag.