CSS/HTML (non-JS) Carousel button issue

I have been trying to create a non-JS (CSS/HTML) carousel but am having difficulty with button placement and getting the style uniform across browsers.

The original code is here: https://codepen.io/maheshambure21/pen/qZZrxy

I would like supplant with the following example which works in both Safari and Firefox:
https://modecss.dev/pure-css-custom-styled-radio-buttons/

My code is here:
https://codepen.io/Hedde2/pen/abrYyVZ
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CSS/HTML (non-JS) Carousel button issue WordPress ...