sidetoc.css

/* Allocate a single column when the width of the page is small. */
.post-single {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    grid-column-gap: 20px;
}

/* Allocate two columns when there is enough width. *
 * The ToC is placed in the second column, while the rest of
 * the children are placed in the first column. */
@media (min-width: 1200px) {
    .post-single {
        grid-template-columns: minmax(0, 3fr) minmax(0, 1fr);
    }
    .post-single .toc {
        grid-column: 2;
        position: sticky;
        top: 10px;
    }
}

.post-single .post-header {
    grid-column: 1;
    width: 100%;
}
.post-single .entry-cover {
    grid-column: 1;
}
.post-single .post-content {
    grid-column: 1;
}
.post-single .post-footer {
    grid-column: 1;
}
.post-single .toc {
    height: fit-content;
    grid-row: span 3;
}
/* Make the ToC scrollable */
.post-single .toc #TableOfContents {
    overflow-y: auto;
    overflow-x: auto;
    padding-left: 20px;
    max-height: 70vh;
}

.post-single .toc .inner {
    margin: 5px;
    padding: 0;
}