Material Icons variants

When using variants of Material Icons, like Outlined for instance, icons won't work because explicitly references 'Material Icons' family font:

.custom-checkbox .custom-control-label::after {
...
font-family: 'Material Icons';
... }

So, when including
``

you should use:

.custom-checkbox .custom-control-label::after {
...
font-family: 'Material Icons', 'Material Icons Outlined';
... }

My proposal is to include all possible variants of https://material.io/resources/icons/ in 'font-family'.