Styling

Style Structure

A Style has five optional components:

style := &werkbook.Style{
    Font:      &werkbook.Font{...},
    Fill:      &werkbook.Fill{...},
    Border:    &werkbook.Border{...},
    Alignment: &werkbook.Alignment{...},
    NumFmt:    "...", // or NumFmtID
}

Styles are whole objects. Calling SetStyle replaces the cell’s style pointer with the value you pass. If you want to preserve part of an existing style, read it first, modify it, then write it back.

style, _ := sheet.GetStyle("A1")
if style == nil {
    style = &werkbook.Style{}
}
style.Font = &werkbook.Font{Bold: true}
sheet.SetStyle("A1", style)

Fonts

sheet.SetStyle("A1", &werkbook.Style{
    Font: &werkbook.Font{
        Name:      "Calibri",
        Size:      14,
        Bold:      true,
        Italic:    false,
        Underline: true,
        Color:     "FF0000", // red, 6-char RGB hex
    },
})

Fill Colors

Set a solid background fill:

sheet.SetStyle("B2", &werkbook.Style{
    Fill: &werkbook.Fill{
        Color: "FFFF00", // yellow
    },
})

Colors are 6-character RGB hex strings (without the # prefix).

Borders

Each side of a cell can have its own style and color:

sheet.SetStyle("C3", &werkbook.Style{
    Border: &werkbook.Border{
        Top:    werkbook.BorderSide{Style: werkbook.BorderThin, Color: "000000"},
        Bottom: werkbook.BorderSide{Style: werkbook.BorderMedium, Color: "000000"},
        Left:   werkbook.BorderSide{Style: werkbook.BorderThin, Color: "CCCCCC"},
        Right:  werkbook.BorderSide{Style: werkbook.BorderThin, Color: "CCCCCC"},
    },
})

Available border styles:

Constant	Style
BorderNone	No border
BorderThin	Thin line
BorderMedium	Medium line
BorderThick	Thick line
BorderDashed	Dashed line
BorderDotted	Dotted line
BorderDouble	Double line

Alignment

sheet.SetStyle("D4", &werkbook.Style{
    Alignment: &werkbook.Alignment{
        Horizontal: werkbook.HAlignCenter,
        Vertical:   werkbook.VAlignTop,
        WrapText:   true,
    },
})

Horizontal options: HAlignGeneral, HAlignLeft, HAlignCenter, HAlignRight

Vertical options: VAlignBottom, VAlignCenter, VAlignTop

Number Formats

Apply custom number formats using spreadsheet number format strings:

// Currency
sheet.SetStyle("E1", &werkbook.Style{NumFmt: "$#,##0.00"})

// Percentage
sheet.SetStyle("E2", &werkbook.Style{NumFmt: "0.00%"})

// Date
sheet.SetStyle("E3", &werkbook.Style{NumFmt: "yyyy-mm-dd"})

// Thousands separator
sheet.SetStyle("E4", &werkbook.Style{NumFmt: "#,##0"})

You can also use built-in format IDs with NumFmtID (0–163).

Range Styles

Apply a style to an entire range at once:

headerStyle := &werkbook.Style{
    Font: &werkbook.Font{Bold: true, Color: "FFFFFF"},
    Fill: &werkbook.Fill{Color: "333333"},
    Alignment: &werkbook.Alignment{Horizontal: werkbook.HAlignCenter},
}

sheet.SetRangeStyle("A1:D1", headerStyle)

SetRangeStyle creates any missing cells in the range so the style has somewhere to live.

Reading Styles

style, _ := sheet.GetStyle("A1")
if style != nil && style.Font != nil {
    fmt.Printf("Font: %s %.0fpt\n", style.Font.Name, style.Font.Size)
}

GetStyle returns nil for default-styled or nonexistent cells.

Full Example

// Style a header row
sheet.SetRangeStyle("A1:E1", &werkbook.Style{
    Font:      &werkbook.Font{Bold: true, Size: 12, Color: "FFFFFF"},
    Fill:      &werkbook.Fill{Color: "2B579A"},
    Alignment: &werkbook.Alignment{Horizontal: werkbook.HAlignCenter},
    Border: &werkbook.Border{
        Bottom: werkbook.BorderSide{
            Style: werkbook.BorderMedium,
            Color: "1A3A6B",
        },
    },
})

// Style currency column
for row := 2; row <= 10; row++ {
    cell := fmt.Sprintf("D%d", row)
    sheet.SetStyle(cell, &werkbook.Style{
        NumFmt:    "$#,##0.00",
        Alignment: &werkbook.Alignment{Horizontal: werkbook.HAlignRight},
    })
}