CSS :indeterminate pseudo selector

:indeterminate is a pseudo-class selector in CSS named for a state that is neither checked nor unchecked.

?It’s that in-between state that we might consider the “Maybe” between “Yes” and “No” options. The state is not fully determined, hence the name: indeterminate.

there is no way to set a checkbox to an indeterminate state in HTML.

:indeterminate can apply to radio buttons at the group level, where the entire group is considered to be in an indeterminate state if no option is selected.