Product Landing Page not detecting CSS Flexbox and Media Query

Tell us what’s happening:
Product Landing Page not detecting CSS Flexbox or Media Queries despite passing tests on Codepen.

The media query works as tested in Codepen, it’s just not being detected.

@media (max-width: 900px) {
  .sub-options {
    display: flex;
    flex-direction: column;
  }

  .spacer {
    height: 50px;
  }
}

I’ve read other forum posts about something related to connecting the code to a live server, but I’m not sure how that helps me get the check mark for the certification progress in FCC. Any help would be appreciated.

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:100.0) Gecko/20100101 Firefox/100.0

Challenge: Build a Product Landing Page

Link to the challenge:

Did you see this note at the bottom of the instructions?

Note: Be sure to add <link rel="stylesheet" href="styles.css"> in your HTML to link your stylesheet and apply your CSS”

Believe it or not, I had it twice. I deleted one and it fixed the error. Thank you!