claude-code-skills-reference/excel-automation/references/formatting-reference.md

Excel Formatting Quick Reference

Font Colors (RGB)

Use Case	Color Name	RGB Code	openpyxl
User input / assumption	Blue	0000FF	Font(color="0000FF")
Calculated value	Black	000000	Font(color="000000")
Cross-sheet reference	Green	008000	Font(color="008000")
Section header text	White	FFFFFF	Font(color="FFFFFF")
Title text	Dark Blue	1F4E79	Font(color="1F4E79")
Subtitle text	Dark Gray	404040	Font(color="404040")
Negative values	Red	FF0000	Font(color="FF0000")

Fill Colors (RGB)

Use Case	Color Name	RGB Code	openpyxl
Section header background	Dark Blue	4472C4	PatternFill("solid", fgColor="4472C4")
Sub-header / alternating row	Light Blue	D9E1F2	PatternFill("solid", fgColor="D9E1F2")
Input cell highlight	Light Green	E2EFDA	PatternFill("solid", fgColor="E2EFDA")
Clean background	White	FFFFFF	PatternFill("solid", fgColor="FFFFFF")
Alternating row	Light Gray	F2F2F2	PatternFill("solid", fgColor="F2F2F2")

Sensitivity Table Gradient Fills

Level	Color Name	RGB Code	Meaning
Worst	Deep Red	F4CCCC	Far below target
Below	Light Red	FCE4D6	Below target
Neutral	Light Yellow	FFF2CC	Near target
Above	Light Green	D9EAD3	Above target
Best	Deep Green	B6D7A8	Far above target

Conditional Formatting (ColorScaleRule)

from openpyxl.formatting.rule import ColorScaleRule

# Red → Yellow → Green (3-color scale)
rule = ColorScaleRule(
    start_type="min", start_color="F8696B",
    mid_type="percentile", mid_value=50, mid_color="FFEB84",
    end_type="max", end_color="63BE7B",
)
ws.conditional_formatting.add("B2:F6", rule)

# Red → Green (2-color scale)
rule = ColorScaleRule(
    start_type="min", start_color="F8696B",
    end_type="max", end_color="63BE7B",
)

Number Format Strings

Format	Code	Example Output
Currency (no decimals)	'$#,##0'	$1,234
Currency (2 decimals)	'$#,##0.00'	$1,234.56
Thousands	'$#,##0,"K"'	$1,234K
Millions	'$#,##0.0,,"M"'	$1.2M
Percentage (1 decimal)	'0.0%'	12.3%
Percentage (2 decimals)	'0.00%'	12.34%
Number with commas	'#,##0'	1,234
Multiplier	'0.0x'	1.5x
Accounting	'_($* #,##0_);_($* (#,##0);_($* "-"_);_(@_)'	$ 1,234
Date	'YYYY-MM-DD'	2026-03-01
Negative in red	'#,##0;[Red]-#,##0'	-1,234 (red)

Border Styles

Style	Side Code	Use Case
Thin gray	Side(style="thin", color="B2B2B2")	Row separators
Medium black	Side(style="medium", color="000000")	Section separators
Double black	Side(style="double", color="000000")	Final totals
Thin black	Side(style="thin", color="000000")	Grid lines

Available style values: 'thin', 'medium', 'thick', 'double', 'dotted', 'dashed', 'hair'

Column Width Guidelines

Content Type	Recommended Width
Short label	12-15
Currency value	14-16
Percentage	10-12
Date	12
Long description	25-35
Auto-fit formula	max(10, min(len(str(max_value)) + 2, 20))

Alignment Presets

from openpyxl.styles import Alignment

CENTER = Alignment(horizontal="center", vertical="center")
RIGHT = Alignment(horizontal="right", vertical="center")
LEFT = Alignment(horizontal="left", vertical="center")
WRAP = Alignment(horizontal="left", vertical="top", wrap_text=True)

Font Presets (Calibri 10pt Base)

from openpyxl.styles import Font

# Standard
REGULAR = Font(size=10, name="Calibri")
BOLD = Font(size=10, name="Calibri", bold=True)
ITALIC = Font(size=10, name="Calibri", italic=True)

# Headers
SECTION_HEADER = Font(size=12, name="Calibri", bold=True, color="FFFFFF")
TITLE = Font(size=14, name="Calibri", bold=True, color="1F4E79")

# Semantic (investment banking convention)
INPUT = Font(size=10, name="Calibri", color="0000FF")          # User inputs
CALC = Font(size=10, name="Calibri", color="000000")           # Formulas
XREF = Font(size=10, name="Calibri", color="008000")           # Cross-references