Change AG Grid header and body checkbox colors separately

Question

I have an AG Grid table with checkboxes at the left of each row to select that row, as well as a checkbox in the header to select All rows. I want the selected checkboxes on the individual rows to have a dark purple background with a white check mark, and the Select All checkbox in the header to have a white background with a black check mark. Using the following CSS, I'm able to correctly set the colors for the individual row checkboxes, and I can set the background of the header checkbox to white, but I can't figure out how to independently change the color of the check mark in the header from white to black.

.ag-theme-alpine .ag-checkbox-input-wrapper.ag-checked::after {
  color: $bg-dark-blue !important;
}

.ag-header-cell .ag-checkbox-input-wrapper.ag-checked::after {
  color: $white !important;
}