Use Media Queries to Create Responsive Layouts... What actually be the query?

Tell us what’s happening:

Your code so far


<style>
  .item1 {
    background: LightSkyBlue;
    grid-area: header;
  }
  
  .item2 {
    background: LightSalmon;
    grid-area: advert;
  }
  
  .item3 {
    background: PaleTurquoise;
    grid-area: content;
  }
  
  .item4 {
    background: lightpink;
    grid-area: footer;
  }
  
  .container {
    font-size: 1.5em;
    min-height: 300px;
    width: 100%;
    background: LightGray;
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: 50px auto 1fr auto;
    grid-gap: 10px;
    grid-template-areas:
      "header"
      "advert"
      "content"
      "footer";
  }
  
  @media (min-width: 300px){
    .container{
      grid-template-columns: auto 1fr;
      grid-template-rows: auto 1fr auto;
      grid-template-areas:
        "advert header"
        "advert content"
        "advert footer";
    }
  }
  
  @media (min-width: 400px){
    .container{
      /* change the code below this line */
    grid-template-columns: auto;
    grid-template-rows: auto auto;
      grid-template-areas:
        "advert header"
        "advert content"
        "advert footer";
    
    /* change the code above this line */
    }
  }
</style>
  
<div class="container">
  <div class="item1">header</div>
  <div class="item2">advert</div>
  <div class="item3">content</div>
  <div class="item4">footer</div>
</div>

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/responsive-web-design/css-grid/use-media-queries-to-create-responsive-layouts

I had explained this earlier, you can have a look at this,