How can I make a CSS grid layout responsive to different screen sizes?

<!-- BEGIN COPY / PASTE -->
    <style>
      .grid-container {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
      }

      @media (min-width: 600px) {
        .grid-container {
          grid-template-columns: repeat(3, 1fr);
        }
      }

      @media (min-width: 900px) {
        .grid-container {
          grid-template-columns: repeat(4, 1fr);
        }
      }
    </style>

    <div class="grid-container">
      <div>Item 1</div>
      <div>Item 2</div>
      <div>Item 3</div>
      <div>Item 4</div>
      <div>Item 5</div>
      <div>Item 6</div>
    </div>
    <!-- END COPY / PASTE -->