段々

1. Origins, structure, and basic meaning

• Structure: 段々 (だんだん) is an adverb meaning gradually or little by little.
• Basic usage: 段々上手になる modifies improving skill, while 段々暗くなる modifies the sky's darkening.

2. Common pitfalls and similar expressions

• Gradual change before なる
  • In both phrases the adverb precedes a change expression with なる and describes the pace, not merely the final state.