# Fixing Style Bugs Introduced by Lovable Code Regeneration - Tool: Lovable - Difficulty: Intermediate - Fix time: ~10 min - Compatibility: All Lovable projects (Tailwind CSS + shadcn/ui) - Last updated: March 2026 ## TL;DR When Lovable regenerates code, it sometimes resets custom styles, changes Tailwind classes, or introduces CSS specificity conflicts that break your design. Prevent this by storing theme customizations in Design view > Themes, adding style preservation rules to AGENTS.md, and using version history to compare before/after changes. If styles break, revert to the previous version and re-prompt with explicit instructions to preserve existing styling. ## Why Lovable regeneration overrides your custom style changes Lovable's AI builds features by modifying component files. When you ask for a change that touches a component you previously styled, the AI may replace or modify the Tailwind classes you carefully set. This happens because the AI generates the entire component (or large sections of it) fresh, using its own styling defaults rather than preserving your customizations. Another common issue is theme resets. If you customized colors or fonts in Design view > Themes, those changes are stored in CSS variables. But if a prompt causes the AI to modify the theme configuration or regenerate base styles, your customizations may be overwritten. CSS specificity conflicts also arise when the AI adds new styles that compete with existing ones. For example, if you set a card background to bg-blue-50 and the AI adds bg-white to the same element, the last class wins in Tailwind, effectively overriding your custom color. - The AI regenerates a component and replaces your custom Tailwind classes with its defaults - A prompt touches the theme configuration and resets custom colors or fonts - New Tailwind classes are added that override existing custom classes on the same element - The AI removes or changes CSS variable definitions that your theme depends on - Visual Edits made through Design view are overwritten by a subsequent Agent Mode prompt ## Error messages you might see **Custom colors or fonts reverted to defaults after a Lovable edit** The AI modified the theme configuration or regenerated components with default styling. Check Design view > Themes to see if your custom values are still there. If not, revert to the previous version. **Background color changed unexpectedly after adding a feature** The AI added a new background class that overrides your custom one. In Tailwind, when two background classes are on the same element, the last one wins. Remove the unwanted class. **Layout spacing changed after regeneration** The AI replaced padding or margin classes during regeneration. Check the component's className for changed spacing utilities (p-4 vs p-6, gap-4 vs gap-2, etc.). ## Before you start - A Lovable project where styles broke after an AI code generation - Access to version history to compare before and after the style change - Familiarity with Design view > Themes for theme-level customizations ## How to fix it ### 1. Use Design view Themes tab for theme-level customizations *Theme customizations in Design view are stored as CSS variables that are less likely to be overwritten by component-level changes* Open Design view by clicking the + button next to Preview and selecting Design view. Go to the Themes tab. Here you can set your core colors (primary, secondary, background, text), fonts, spacing scale, and border radius. These settings generate CSS variables that are used by all shadcn/ui components. Changes here are more resilient to AI regeneration because the AI typically generates components that reference these variables rather than hardcoded values. Before: ``` // Custom colors hardcoded in individual components:

Dashboard

// AI regeneration replaces these with defaults ``` After: ``` // Theme-level colors set in Design view > Themes:

Dashboard

// These reference CSS variables that survive regeneration ``` **Expected result:** Your custom colors persist across AI regenerations because components reference theme variables, not hardcoded values. ### 2. Add style preservation rules to AGENTS.md *AGENTS.md rules tell the AI which styles and theme settings to preserve during code generation* Add a Style Preservation section to your AGENTS.md file listing specific styling rules the AI should follow. Include your color scheme, font choices, spacing conventions, and any custom CSS classes. The AI reads this file at the start of every session and follows these rules when generating or modifying code. Before: ``` // No style rules in AGENTS.md // AI uses its own styling defaults during regeneration ``` After: ``` # AGENTS.md — Style Preservation Rules ## Theme (DO NOT CHANGE): - Primary color: use 'primary' CSS variable (currently blue-600) - Background: use 'background' CSS variable (currently white) - Font: Inter for body, system fonts for headings - Border radius: rounded-lg (8px) for cards, rounded-md for inputs ## Spacing conventions: - Page padding: p-6 on mobile, md:p-8 on desktop - Card padding: p-4 - Gap between elements: gap-4 (16px) - Section spacing: space-y-8 ## NEVER change: - Do not modify Design view > Themes settings - Do not replace bg-primary with hardcoded color values - Do not change the font family - Preserve all existing className strings unless explicitly asked to change them ``` **Expected result:** The AI follows your style rules and preserves existing styling during code generation. ### 3. Use version history to detect and revert style changes *Version history lets you compare before and after to identify exactly which styles changed* When styles break after a generation, scroll up in the Lovable chat to find the version before the style change. Click Revert to restore that version. Then re-send your prompt with explicit instructions to preserve existing styles. Add a constraint like 'Do not change any existing className values or theme settings' to your prompt. Before: ``` // After regeneration: styles are broken // Not sure which specific classes changed ``` After: ``` // Step 1: Scroll up → find last version with correct styles // Step 2: Click Revert // Step 3: Re-send prompt with style preservation constraint: // 'Add the search bar to @src/pages/Dashboard.tsx. // Do not change any existing className values. // Do not modify the theme or color scheme. // Preserve all current spacing and layout.' ``` **Expected result:** The feature is added without breaking existing styles. The constraint prevents the AI from modifying your styling. ### 4. Use Visual Edits for styling changes after code generation *Visual Edits in Design view modify styles directly without triggering a full code regeneration* After the AI generates a feature, use Design view > Visual Edits to fine-tune the styling. Visual editing lets you select elements, adjust margins/padding, change colors/fonts, and modify text without going through the AI. These changes do not cost credits and are applied directly to the code. This avoids the risk of the AI regenerating your carefully styled components. If your project has complex theme customization across many components, RapidDev's engineers have managed styling consistency across 600+ Lovable projects. Before: ``` // Using Agent Mode to fix a small style issue: // Prompt: 'Make the card background lighter' // Risk: AI regenerates the entire card component, changing other styles ``` After: ``` // Using Visual Edits instead: // 1. Click + next to Preview → Design view // 2. Click Visual Edits tab // 3. Click the card element // 4. Change background color directly // No AI regeneration, no risk of style changes elsewhere ``` **Expected result:** The background color changes without affecting any other styles. No credits used, no regeneration risk. ## Complete code example File: `AGENTS.md` ```markdown # Style and Theme Rules ## Design System This project uses Design view > Themes for all core styling. Do NOT override theme variables with hardcoded values. ## Color Palette (from Theme) - Primary: bg-primary, text-primary, border-primary - Secondary: bg-secondary, text-secondary - Background: bg-background - Foreground: text-foreground - Muted: bg-muted, text-muted-foreground - Destructive: bg-destructive (for errors/warnings) ## Typography - Headings: text-2xl font-bold (h1), text-xl font-semibold (h2) - Body: text-sm or text-base - Muted text: text-muted-foreground - Links: text-primary hover:underline ## Spacing - Page wrapper: max-w-7xl mx-auto p-6 md:p-8 - Card: rounded-lg border p-4 or p-6 - Section gaps: space-y-8 between sections, space-y-4 within sections - Element gaps: gap-4 in flex/grid containers ## Component Styling - Use shadcn/ui components for all UI elements - Use Tailwind utilities for layout and spacing - Never use inline styles - Never use !important ## PRESERVATION RULES - Do not modify existing className strings unless explicitly asked - Do not change Design view > Themes settings - Do not add new global CSS that could affect existing components - Do not change the font family - When adding new components, match the existing visual style ``` ## Best practices - Use Design view > Themes for all core styling (colors, fonts, spacing) — these are more resilient to AI regeneration - Add style preservation rules to AGENTS.md listing your design system and what should not change - Use Visual Edits for small styling adjustments — they do not trigger code regeneration and cost no credits - Reference theme CSS variables (bg-primary, text-foreground) instead of hardcoded colors in components - Add constraints to prompts: 'Do not change any existing className values or theme settings' - Check version history after every code generation to verify styles are intact - Keep a record of your custom style values (colors, fonts, spacing) outside of Lovable as a reference - If using custom CSS in src/index.css, add a comment marking which styles are custom to help the AI identify them ## Frequently asked questions ### Why did Lovable change my custom styles during regeneration? When the AI regenerates a component, it writes new code based on its defaults. It may replace your custom Tailwind classes with its own choices unless you explicitly tell it to preserve existing styles. Add preservation rules to AGENTS.md and include style constraints in your prompts. ### How do I prevent Lovable from overwriting my theme? Set your theme using Design view > Themes, which stores values as CSS variables. Reference these variables in code (bg-primary, text-foreground) instead of hardcoded colors. Add a rule to AGENTS.md: 'Do not modify Design view > Themes settings.' ### Can I use Visual Edits instead of prompts for styling? Yes. Design view > Visual Edits lets you click elements and adjust their styles directly without AI regeneration. This costs no credits and carries no risk of breaking other styles. Use it for fine-tuning after AI code generation. ### How do I detect which styles changed after regeneration? Use version history to compare the component before and after. Scroll up in chat to find the previous version and compare the className values. Focus on background, spacing, font size, and color classes. ### Should I use custom CSS or Tailwind classes? Use Tailwind classes whenever possible. They are easier for the AI to read and preserve. Custom CSS in src/index.css is more likely to be overwritten or conflicted with during regeneration. ### What if I can't fix this myself? If regeneration broke styles across many components and restoring them manually is too complex, RapidDev's engineers can audit and fix your styling. They have restored consistent design systems across 600+ Lovable projects. --- Source: https://www.rapidevelopers.com/lovable-issues/fixing-style-bugs-introduced-by-lovable-regeneration © RapidDev — https://www.rapidevelopers.com/lovable-issues/fixing-style-bugs-introduced-by-lovable-regeneration