details{margin:0 20px 10px;padding:0}summary::-webkit-details-marker{display:none}summary{margin:0;padding:10px;cursor:pointer;display:flex;justify-content:space-between;align-items:center;list-style:none}summary::after{content:'+';font-size:1.5em;font-weight:700;margin-right:10px;transition:transform .3s ease}details[open] summary::after{content:'×'}details>:not(summary){padding:10px}ul{margin:0}