how to make a grid display when responsive code example

Example 1: responsive css grid

@supports (display: grid) {
  main { 
    max-width: 10000px;
    margin: 0;
  }
  .grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 2fr));
    grid-gap: 1rem;
  }
}

Example 2: css grid responsive

grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));