v0.4.0

• Not a breaking change per se, but will cause a significant visual difference for the following:
  • Images that have the img-outline class applied, as the border and shadow style has changed from a thin grey line, to a slightly thicker line of the theme's accent colour
  • This same border and box-shadow treatment also applies to Mermaid diagrams which use the MermaidWrapper component, and the LargeImg component
• Orange theme title highlight colour has been changed to orange instead of teal