Since v2.7.0
Use a custom icon for the TOC title icon.
Adjust the --jtoc-title-icon-size CSS Variable to set a custom icon size.
add_filter('joli_toc_title_icon', 'my_custom_title_icon', 10, 1);
function my_custom_title_icon( $icon ){
return <<<HTML
<style>
.--has-icon svg {--jtoc-title-icon-size: 24px;}
</style>
<svg viewBox="0 0 1024 1024" class="icon" version="1.1" xmlns="http://www.w3.org/2000/svg" fill="#000000"><g id="SVGRepo_bgCarrier" stroke-width="0"></g><g id="SVGRepo_tracerCarrier" stroke-linecap="round" stroke-linejoin="round"></g><g id="SVGRepo_iconCarrier"><path d="M91.89 238.457c-29.899 0-54.133 24.239-54.133 54.134 0 29.899 24.234 54.137 54.133 54.137s54.138-24.238 54.138-54.137c0-29.896-24.239-54.134-54.138-54.134z" fill="#E5594F"></path><path d="M91.89 462.463c-29.899 0-54.133 24.239-54.133 54.139 0 29.895 24.234 54.133 54.133 54.133s54.138-24.238 54.138-54.133c0-29.9-24.239-54.139-54.138-54.139z" fill="#C45FA0"></path><path d="M91.89 686.475c-29.899 0-54.133 24.237-54.133 54.133 0 29.899 24.234 54.138 54.133 54.138s54.138-24.238 54.138-54.138c0-29.896-24.239-54.133-54.138-54.133z" fill="#F39A2B"></path><path d="M941.26 234.723H328.964c-28.867 0-52.263 23.4-52.263 52.268v3.734c0 28.868 23.396 52.269 52.263 52.269H941.26c28.869 0 52.269-23.401 52.269-52.269v-3.734c-0.001-28.868-23.4-52.268-52.269-52.268z" fill="#F0D043"></path><path d="M941.26 682.74H328.964c-28.867 0-52.263 23.399-52.263 52.268v3.734c0 28.863 23.396 52.269 52.263 52.269H941.26c28.869 0 52.269-23.405 52.269-52.269v-3.734c-0.001-28.868-23.4-52.268-52.269-52.268z" fill="#4A5699"></path><path d="M709.781 458.729H328.964c-28.867 0-52.263 23.4-52.263 52.269v3.734c0 28.873 23.396 52.269 52.263 52.269h380.817c28.866 0 52.271-23.396 52.271-52.269v-3.734c0.001-28.869-23.405-52.269-52.271-52.269z" fill="#E5594F"></path></g></svg>
HTML;
}