<Dark Themed Excel Spreadsheet>
1. Base White - 
                            
                            #FFFFFF
                         - A clean, bright white base for text and highlights.
2. Deep Charcoal - 
                            
                            #333333
                         - A very dark gray that provides a strong contrast against the white.
3. Midnight Blue - 
                            
                            #001F4D
                         - A deep blue that adds a sophisticated touch while maintaining readability.
4. Slate Gray - 
                            
                            #708090
                         - A muted, cool gray that can be used for secondary elements and backgrounds.
5. Emerald Green - 
                            
                            #2ECC71
                         - A vibrant green that draws attention to important data without overwhelming.
6. Crimson Red - 
                            
                            #C0392B
                         - A bold red for alerts or highlighting critical information.

This color palette is designed to create a dark-themed aesthetic for Excel spreadsheets while using white as the base. The combination of deep grays and blues provides a professional look, while pops of vibrant colors like emerald green and crimson red help to highlight essential data points.

What specific data types or themes will you be working with in your Excel spreadsheets? Do you have any particular elements you want to emphasize (like headers, charts, etc.)?