modifying-theme-json

# Power BI Report Themes ## Why Themes Matter A report without a well-designed theme accumulates formatting debt. Every visual ends up with its own bespoke title size, shadow toggle, border style, and hardcoded colors in `visual.json`. This creates three problems: 1. **Inconsistency.** Visuals drift apart as authors format each one individually. One card has 14pt titles, another has 12pt; one chart has shadows, another doesn't. The report looks unfinished. 2. **Fragility.** Rebranding or updating the visual style means touching every visual.json individually. A report with 40 visuals across 8 pages means 40 files to edit. With a theme, it's one file. 3. **Bloated visual JSON.** Each bespoke override adds lines to visual.json, making reports harder to diff, review, and maintain. A clean visual.json should contain field bindings, position, and conditional formatting; everything else should come from the theme. Reports using the default Power BI theme or a minimal custom theme (just `dataColors` and a name) are leaving most formatting to Power BI's built-in defaults, which change between Desktop releases. A well-designed theme locks in the intended appearance. **Signs a theme needs attention:** - Many visuals have `objects` or `visualContainerObjects` with redundant formatting - Visuals of the same type look inconsistent (different title fonts, shadows on some but not others) - The theme JSON has few or no `visualStyles` entries - The report uses a built-in theme like "Defa...