Can't go further at grid-template-areas

This is the 14th challenge at CSS Grid. I am supposed to replace the advert in the second row with a period. But once I do that, it still gives me this message: “container class should have a grid-template-areas property similar to the preview but has . instead of the advert area.”

Here is the code:

  .container {
    font-size: 40px;
    min-height: 300px;
    width: 100%;
    background: LightGray;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    grid-template-rows: 1fr 1fr 1fr;
    grid-gap: 10px;
    /* Only change code below this line */
      "header header header"
      ". content content"
      "footer footer footer";
    /* Only change code above this line */

Removing the comments helped and I passed the challenge.

yes, there is a know bug. It will be fixed.