Here are calmer and darker accent versions of the bold colors suitable for borders around the buttons:

1. Deep Red - #8B0000 : A dark shade of red that provides a muted yet strong outline, bringing attention to the bold red button without overwhelming it.

2. Midnight Blue - #003366 : A deep blue that offers a calm and sophisticated accent, creating a nice contrast with the vibrant blue button.

3. Dark Forest Green - #005C00 : A rich, dark green that complements the vivid green button while providing a grounded, nature-inspired edge.

Here’s how these accent colors fit into your palette:

 < Fantasy Punk Dark Accents >
1. Deep Red - 
          
          #8B0000
        - A dark red that offers a strong, muted outline for the bold red button.
2. Midnight Blue - 
          
          #003366
        - A deep blue that adds sophistication and calmness as an accent for the bold blue button.
3. Dark Forest Green - 
          
          #005C00
        - A rich green that grounds the vivid green button with a natural vibe.

These darker accents will enhance the appearance of your buttons, providing structure while maintaining the overall aesthetic of the Fantasy Punk theme.

Do these darker shades work for your needs? Would you like additional suggestions or modifications for any specific elements in your design?