.book-tool__heading {
  box-sizing: border-box;
  padding-inline-start: 10px;
}

/* Keep saved rich text inside the text page's available flex width. */
.book-tool .book-tool__paper--text .book-tool__story-text {
  min-width: 0;
  max-width: 100%;
  overflow-x: hidden;
  overflow-wrap: anywhere;
}
.book-tool .book-tool__story-text--rich :where(*) {
  max-width: 100%;
  overflow-wrap: anywhere;
}

@container (max-width: 600px) {
  /* Editor font tags and inline sizes must follow the responsive reader size. */
  .book-tool .book-tool__paper--text .book-tool__story-text--rich :where(*) {
    font-size: inherit !important;
    line-height: inherit !important;
    white-space: normal !important;
  }
}