Create a CSS only accordion using existing Stylesheet

Need to build a pure CSS and html vertical accordion (to expand/collapse grid content lists see https://codepen.io/pen/wvoEvqG for example) that can work in any Drupal html page. Must use existing styles. CSS can not be changed or edited. Any exception must be because the style does not exist.
Must work in Chrome, Edge, Firefox, Opera and Safari
Must be responsive and aria accessible