fix: frontmatter coercion (empty string is falsy)

Jacky Zhao

2023-12-09 2c69b0c97d40f76363d20478cb799ce4b7518e56

 quartz/components/styles/legacyToc.scss

@@ -12,7 +12,7 @@
      margin: 0;
    }
  }
    

  & ul {
    list-style: none;
    margin: 0.5rem 1.25rem;