.Index_Grid {
  display: block; /* or flex, or whatever you want for mobile */
}

/* Desktop-specific: apply grid */
@media (min-width: 800px) {
  .Index_Grid {
    display: grid;
    grid-template-columns: 1fr 45rem 1fr;
    grid-template-rows: auto;
    grid-template-areas: "Index_Column_1 Index_Column_2 Index_Column_3";
  }
}

    .Index_Column_1 {
    grid-area: Index_Column_1;
  }
  
    .Index_Column_2 {
    grid-area: Index_Column_2;
  }

  .Index_Column_3 {
    grid-area: Index_Column_3;
  }