v1 - CodePen - Multilevel dropdown menu with simple HTML and CSS

Human_being
- Man
- Woman
  - 2a
  - 2b
    - 3a
    - 3b
      - 4a
      - 4b
    - 3b
    - 3c
    - 3d
  - 2c
- Child
- Teen
- Adult
- 1c
  - 1c-2a
  - 1c-2b
- 1d
  - 1d-2a
  - 1d-2b