.grid-container
{
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    grid-auto-rows: 100px;
    gap: 10px;
}
.box
{
    background-color: lightblue;
    border: 1px solid black;
    display: flex;
    justify-content: center;
    align-items: center;
}