.f13-toc { background: #fafafa; border: 1px solid #ccc; padding: 0px; }
.f13-toc summary { cursor: pointer; font-weight: bold; padding: 10px 20px; }
.f13-toc summary:after { content: '\021B4'; right: 35px; position: absolute; }
.f13-toc[open] summary:after { content: '\021B5'; }
.f13-toc > ol { padding-left: 50px; padding-top: 10px; border-top: 1px solid #ccc; }
.f13-toc ol ol, .f13-toc ol ol ol ol ol { list-style: lower-alpha; }
.f13-toc ol ol ol, .f13-toc ol ol ol ol ol ol { list-style: upper-roman; }
.f13-toc ol ol ol ol { list-style: decimal; }
.f13-toc[open] summary ~ * { animation: sweep .5s ease-in-out; }
@keyframes sweep {
    0% {opacity: 0; margin-left: -10px}
    100%  {opacity: 1; margin-left: 0px}
}