Pure CSS only collapsible elements. How to create accordion without JavaScript

Pure CSS collapsible (with on click) containers/elements/whateva. HTML Code: <div id="elem"></div> <a href="#" class="par cac1">Tab 1</a> <a href="#" class="par cac2">Tab 2</a> <a href="#" class="par cac3">Tab 3</a> <h1 class="zzz1">ELEMENT 1</h1> <h1 class="zzz2">ELEMENT 2</h1> <h1 class="zzz3">ELEMENT 3</h1>…