Here’s a color palette inspired by a frog monster in a Gravity Falls art style, expanding upon the hex code #319179 :

 <Frog Monster Theme>
1. Swamp Green - 
                            
                            #319179
                         - A vibrant green reminiscent of the swampy habitats where frogs thrive.
2. Mud Brown - 
                            
                            #4B3D27
                         - A deep, earthy brown that reflects the muddy grounds of a bog.
3. Lily Pad - 
                            
                            #A8D8B9
                         - A soft, light green that captures the essence of lily pads floating on water.
4. Monster Eye Yellow - 
                            
                            #E1C300
                         - A bright yellow that evokes the eerie shine of a frog monster's eyes.
5. Pond Water - 
                            
                            #2A6B7E
                         - A cool, dark blue that represents the mysterious depths of a pond.
6. Bug Bite Red - 
                            
                            #D94F3D
                         - A bold red that symbolizes a frog monster's appetite for insects.
7. Night Sky Purple - 
                            
                            #4A2C6D
                         - A deep purple that adds a hint of mystery and night-time ambiance to the palette.

This color palette combines earthy tones with vibrant accents, perfect for creating a whimsical yet slightly eerie frog monster character in a Gravity Falls-inspired art style.

What specific elements would you like to focus on in the design? Characters, backgrounds, or something else?