Where do I put this code? #344

/* Set some variables for the entire leaf. */
.longform-leaf {
  --background-primary: white;
  --background-primary-alt: white;
  --background-secondary: white;
  --background-secondary-alt: white;
}

/* Style the editor. */
.longform-leaf .markdown-source-view {
  --background-primary: white;
  --background-primary-alt: white;
  --background-secondary: white;
  --background-secondary-alt: white;
  --text-selection: #aaa;
  --text-normal: black;
  color: black;
  background-color: white;
}

/* Style text selection. */
.longform-leaf .suggestion-item.is-selected {
  background-color: var(--text-accent);
}

/* Style the header of the leaf. */
.longform-leaf .view-header {
  background-color: white;
}

/* Style the text content of the leaf header. */
.longform-leaf .view-header-title {
  --text-normal: black;
}