Sparklines and In-Cell Charts Guide

Help me create sparklines and in-cell visualizations:

**Sparkline Type Needed:**
- [ ] Line sparkline (trends)
- [ ] Column sparkline (comparisons)
- [ ] Win/Loss sparkline (positive/negative)

**Data for Sparklines:**
- Data range: [e.g., B2:M2 for 12 months]
- Number of sparklines: [how many rows of data]
- Data represents: [sales, temperatures, scores, etc.]

**Customization Needed:**
- [ ] Highlight high/low points
- [ ] Show first/last points
- [ ] Show negative in different color
- [ ] Set axis min/max
- [ ] Same scale across all sparklines
- [ ] Custom colors

**Alternative In-Cell Charts:**
- [ ] REPT function bar charts
- [ ] Conditional formatting data bars
- [ ] Unicode character charts
- [ ] Progress indicators

**Context:**
- Where will these appear: [dashboard / report / data table]
- Color preferences: [specify]
- Excel version or Google Sheets: [specify]

Please provide:
1. Sparkline creation steps
2. Customization options
3. Formulas for REPT-based charts
4. Data bar conditional formatting
5. Best practices for in-cell viz
6. When to use each type