Collapsible Table of Contents CSS

.wp-block-rank-math-toc-block {
	position:relative;
}

.wp-block-rank-math-toc-block h2 {
    background: #f1f2f6;
    padding: 10px 12px 10px 18px;
    cursor: pointer;
    font-size: 18px !important;
    font-weight: normal !important;
    position:relative;
    margin-bottom: 0;
}
.wp-block-rank-math-toc-block h2:before {
	display:inline-block;
	content: "";
        width: 0;
	height: 0;
	border-style: solid;
	border-width: 6px 0 6px 12px;
	border-color: transparent transparent transparent #000000;
	margin-right: 8px;
}

.wp-block-rank-math-toc-block nav{
	padding: 10px 10px 0px 10px;
	max-height: 0;
	overflow:hidden;
}
.wp-block-rank-math-toc-block input:checked+h2~nav {
	max-height: 100%;
	overflow:visible;
}