Did you find a solution?

Actually here are some good settings, for making the grid more responsive:

section {
padding: var(--section-padding, 10px 0); /*control spacing between section, adjust 10px*/

} @media (max-width: 991px) { .umb-block-gridarea { --umb-block-grid--grid-columns: 12 !important; --umb-block-grid--area-column-span: 12 !important; --umb-block-grid--area-row-span: 1 !important; } .umb-block-gridarea-container, .umb-block-grid__block--view::part(area-container) { --umb-block-grid--areas-column-gap: 0; --umb-block-grid--areas-row-gap: 0; }

.umb-block-grid__layout-item[data-content-element-type-alias="oneColumnSectionBlock"] .umb-block-grid__layout-container {
    --umb-block-grid--column-gap: 0;
    --umb-block-grid--row-gap: 0;
}

.rich-text {
    columns: inherit;
}
    .rich-text h3, .rich-text p {
        width: 100%;
    }

}

Here's one that works in 11.1. Most px's swapped for em's:-

    section {
    padding: var(--section-padding, 0.6em 0); /*control spacing between section, adjust 10px*/
}

.umb-block-gridlayout-container {
    position: relative;
    display: grid;
    grid-template-columns: repeat(var(--umb-block-grid--grid-columns, 1), minmax(0, 1fr));
    grid-auto-flow: row;
    grid-auto-rows: minmax(3em, -webkit-min-content);
    grid-auto-rows: minmax(3em, min-content);
    -moz-column-gap: var(--umb-block-grid--column-gap, 0);
    column-gap: var(--umb-block-grid--column-gap, 0);
    row-gap: var(--umb-block-grid--row-gap, 0);

}

.umb-block-grid__layout-item {
    position: relative;
    /* For small devices we scale columnSpan by three, to make everything bigger than 1/3 take full width: */
    grid-column-end: span min(calc(var(--umb-block-grid--item-column-span, 1) * 3), var(--umb-block-grid--grid-columns));
    grid-row: span var(--umb-block-grid--item-row-span, 1);
    padding: 0 0 1em 0;
}

.umb-block-grid__area-container, .umb-block-grid__block--view::part(area-container) {
    position: relative;
    display: grid;
    grid-template-columns: repeat(var(--umb-block-grid--area-grid-columns, var(--umb-block-grid--grid-columns, 1)), minmax(0, 1fr));
    grid-auto-flow: row;
    grid-auto-rows: minmax(3em, -webkit-min-content);
    grid-auto-rows: minmax(3em, min-content);
    -moz-column-gap: var(--umb-block-grid--areas-column-gap, 0);
    column-gap: var(--umb-block-grid--areas-column-gap, 0);
    row-gap: var(--umb-block-grid--areas-row-gap, 0);
}
.umb-block-grid__area {
    position: relative;
    height: 100%;
    display: flex;
    flex-direction: column;
    /* For small devices we scale columnSpan by three, to make everything bigger than 1/3 take full width: */
    grid-column-end: span min(calc(var(--umb-block-grid--area-column-span, 1) * 3), var(--umb-block-grid--area-grid-columns));
    grid-row: span var(--umb-block-grid--area-row-span, 1);
}

@media (min-width:1024px) {
    .umb-block-grid__layout-item {
        grid-column-end: span min(var(--umb-block-grid--item-column-span, 1), var(--umb-block-grid--grid-columns));
    }

    .umb-block-grid__area {
        grid-column-end: span min(var(--umb-block-grid--area-column-span, 1), var(--umb-block-grid--area-grid-columns));
    }
}

/**** Custom additions to the default Grid Layout Stylehseet: ****/


/* additional CSS options for area-container and areas: */
.umb-block-grid__area-container, .umb-block-grid__block--view::part(area-container) {
    max-width: var(--my-container-max-width);
    padding: var(--my-container-padding);
    margin-left: auto;
    margin-right: auto;
    --umb-block-grid--areas-column-gap: 2em;
    --umb-block-grid--areas-row-gap: 1em;
}

is working on a reply...