Color Palette for Coding Challenge & Practice. Primary: #22C55E (on-primary: #0F172A). Secondary: #059669 (on-secondary: #FFFFFF). Accent: #D97706 (on-accent: #FFFFFF). Background: #0F172A. Foreground: #FFFFFF. Card: #192134 (card-foreground: #FFFFFF). Muted: #10242E (muted-foreground: #94A3B8). Border: rgba(255,255,255,0.08). Destructive: #DC2626 (on-destructive: #FFFFFF). Ring: #22C55E. Notes: Code green + difficulty amber on dark.