:indeterminate
Targets form elements whose state is neither 'on' nor 'off' (like a checkbox that's been mixed by JavaScript, or a radio group where nothing is selected yet).
Quick example
input[type='checkbox']:indeterminate {
/* Styles a 'half-checked' or 'mixed' checkbox */
opacity: 0.5;
outline: 2px dashed orange;
}:indeterminate Browser Support
Widely available Since 2020 96% global usage
This feature is well established and works across many devices and browser versions. It has been available across browsers since 2020.
Safe to use without fallbacks.
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