Checkboxes showing on the backend, but not on the frontend?

For some reason the opacity of your checkboxes are set to 0 here:
https://naptosa.org.za/wp-content/cache/wpo-minify/1673584766/assets/wpo-minify-header-5bd14718.min.css

change the opacity by adding:

input[type="checkbox"]{
    opacity: 1;
}