html,
body
{
    height: 100vh;
}

main {
    height: 100%;
    max-height: 100vh;
    overflow-x: auto;
    overflow-y: hidden;
}

.auto-grow {
    field-sizing: content; /* Modern CSS solution */
    min-height: 4rem;      /* Optional: Set a minimum height */
    max-height: 10rem;
    /* For older browsers, you may also want to use: */
    resize: none;
}