Styling checkbox (1st tab)

Dear community, dear support,

I was able to address the checkbox at the bottom of the 1st tab with the CSS-class:

.xoo-el-form-label {
accent-color: #e881a6;
}

to change the color of the box (when clicked), but using that same class to change the border-radius does not work ( I tried different values, but “border-radius” in general doesn’t apply. Want to make it complete circle).

Any ideas whether I need to use a different class or different approach here?

Many thanks in advance,
neverdowork