@startuml

class Workbook {
  - sheetnames: List
  - active: Worksheet
  + save()
}

class Worksheet {
  - title: str
  - column_dimensions: DimensionHolder
  - freeze_panes: String
  + cell(row: int, col: int): Cell
  + cell(coord: str): Cell
}

class Cell {
  - value: Any
  - fill: PatternFill
  - font: Font
  - alignment: Alignment
  - border: Border
  - number_format: String
}

class PatternFill {
  - start_color: Color
  - end_color: Color
  - fill_type: String
}

class Font {
  - name: String
  - size: int
  - bold: Bool
}

class Alignment {
  - horizontal: String
  - vertical: String
}

class Border {
  - top: BorderLine
  - bottom: BorderLine
  - left: BorderLine
  - right: BorderLine
}

class BorderLine {
  - style: String
  - color: Color
}

class Color {
  - value: String
}

Workbook "1" --* "1..*" Worksheet : contains
Worksheet "1" --* "1..*" Cell : contains
Cell --o "1" PatternFill : fill
Cell --o "1" Font : font
Cell --o "1" Alignment : alignment
Cell --o "1" Border : border
Border --o "1" BorderLine : top
Border --o "1" BorderLine : bottom
Border --o "1" BorderLine : left
Border --o "1" BorderLine : right
Color --o "1" PatternFill : start_color
Color --o "1" PatternFill : end_color
Color --o "1" BorderLine : color

@enduml