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antigravity-skills-reference/skills/frontend-dev-guidelines/resources/styling-guide.md

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# Styling Guide
Modern styling patterns for using MUI v7 sx prop, inline styles, and theme integration.
---
## Inline vs Separate Styles
### Decision Threshold
**<100 lines: Inline styles at top of component**
```typescript
import type { SxProps, Theme } from '@mui/material';
const componentStyles: Record<string, SxProps<Theme>> = {
container: {
p: 2,
display: 'flex',
flexDirection: 'column',
},
header: {
mb: 2,
borderBottom: '1px solid',
borderColor: 'divider',
},
// ... more styles
};
export const MyComponent: React.FC = () => {
return (
<Box sx={componentStyles.container}>
<Box sx={componentStyles.header}>
<h2>Title</h2>
</Box>
</Box>
);
};
```
**>100 lines: Separate `.styles.ts` file**
```typescript
// MyComponent.styles.ts
import type { SxProps, Theme } from '@mui/material';
export const componentStyles: Record<string, SxProps<Theme>> = {
container: { ... },
header: { ... },
// ... 100+ lines of styles
};
// MyComponent.tsx
import { componentStyles } from './MyComponent.styles';
export const MyComponent: React.FC = () => {
return <Box sx={componentStyles.container}>...</Box>;
};
```
### Real Example: UnifiedForm.tsx
**Lines 48-126**: 78 lines of inline styles (acceptable)
```typescript
const formStyles: Record<string, SxProps<Theme>> = {
gridContainer: {
height: '100%',
maxHeight: 'calc(100vh - 220px)',
},
section: {
height: '100%',
maxHeight: 'calc(100vh - 220px)',
overflow: 'auto',
p: 4,
},
// ... 15 more style objects
};
```
**Guideline**: User is comfortable with ~80 lines inline. Use your judgment around 100 lines.
---
## sx Prop Patterns
### Basic Usage
```typescript
<Box sx={{ p: 2, mb: 3, display: 'flex' }}>
Content
</Box>
```
### With Theme Access
```typescript
<Box
sx={{
p: 2,
backgroundColor: (theme) => theme.palette.primary.main,
color: (theme) => theme.palette.primary.contrastText,
borderRadius: (theme) => theme.shape.borderRadius,
}}
>
Themed Box
</Box>
```
### Responsive Styles
```typescript
<Box
sx={{
p: { xs: 1, sm: 2, md: 3 },
width: { xs: '100%', md: '50%' },
flexDirection: { xs: 'column', md: 'row' },
}}
>
Responsive Layout
</Box>
```
### Pseudo-Selectors
```typescript
<Box
sx={{
p: 2,
'&:hover': {
backgroundColor: 'rgba(0,0,0,0.05)',
},
'&:active': {
backgroundColor: 'rgba(0,0,0,0.1)',
},
'& .child-class': {
color: 'primary.main',
},
}}
>
Interactive Box
</Box>
```
---
## MUI v7 Patterns
### Grid Component (v7 Syntax)
```typescript
import { Grid } from '@mui/material';
// ✅ CORRECT - v7 syntax with size prop
<Grid container spacing={2}>
<Grid size={{ xs: 12, md: 6 }}>
Left Column
</Grid>
<Grid size={{ xs: 12, md: 6 }}>
Right Column
</Grid>
</Grid>
// ❌ WRONG - Old v6 syntax
<Grid container spacing={2}>
<Grid xs={12} md={6}> {/* OLD - Don't use */}
Content
</Grid>
</Grid>
```
**Key Change**: `size={{ xs: 12, md: 6 }}` instead of `xs={12} md={6}`
### Responsive Grid
```typescript
<Grid container spacing={3}>
<Grid size={{ xs: 12, sm: 6, md: 4, lg: 3 }}>
Responsive Column
</Grid>
</Grid>
```
### Nested Grids
```typescript
<Grid container spacing={2}>
<Grid size={{ xs: 12, md: 8 }}>
<Grid container spacing={1}>
<Grid size={{ xs: 12, sm: 6 }}>
Nested 1
</Grid>
<Grid size={{ xs: 12, sm: 6 }}>
Nested 2
</Grid>
</Grid>
</Grid>
<Grid size={{ xs: 12, md: 4 }}>
Sidebar
</Grid>
</Grid>
```
---
## Type-Safe Styles
### Style Object Type
```typescript
import type { SxProps, Theme } from '@mui/material';
// Type-safe styles
const styles: Record<string, SxProps<Theme>> = {
container: {
p: 2,
// Autocomplete and type checking work here
},
};
// Or individual style
const containerStyle: SxProps<Theme> = {
p: 2,
display: 'flex',
};
```
### Theme-Aware Styles
```typescript
const styles: Record<string, SxProps<Theme>> = {
primary: {
color: (theme) => theme.palette.primary.main,
backgroundColor: (theme) => theme.palette.primary.light,
'&:hover': {
backgroundColor: (theme) => theme.palette.primary.dark,
},
},
customSpacing: {
padding: (theme) => theme.spacing(2),
margin: (theme) => theme.spacing(1, 2), // top/bottom: 1, left/right: 2
},
};
```
---
## What NOT to Use
### ❌ makeStyles (MUI v4 pattern)
```typescript
// ❌ AVOID - Old Material-UI v4 pattern
import { makeStyles } from '@mui/styles';
const useStyles = makeStyles((theme) => ({
root: {
padding: theme.spacing(2),
},
}));
```
**Why avoid**: Deprecated, v7 doesn't support it well
### ❌ styled() Components
```typescript
// ❌ AVOID - styled-components pattern
import { styled } from '@mui/material/styles';
const StyledBox = styled(Box)(({ theme }) => ({
padding: theme.spacing(2),
}));
```
**Why avoid**: sx prop is more flexible and doesn't create new components
### ✅ Use sx Prop Instead
```typescript
// ✅ PREFERRED
<Box
sx={{
p: 2,
backgroundColor: 'primary.main',
}}
>
Content
</Box>
```
---
## Code Style Standards
### Indentation
**4 spaces** (not 2, not tabs)
```typescript
const styles: Record<string, SxProps<Theme>> = {
container: {
p: 2,
display: 'flex',
flexDirection: 'column',
},
};
```
### Quotes
**Single quotes** for strings (project standard)
```typescript
// ✅ CORRECT
const color = 'primary.main';
import { Box } from '@mui/material';
// ❌ WRONG
const color = "primary.main";
import { Box } from "@mui/material";
```
### Trailing Commas
**Always use trailing commas** in objects and arrays
```typescript
// ✅ CORRECT
const styles = {
container: { p: 2 },
header: { mb: 1 }, // Trailing comma
};
const items = [
'item1',
'item2', // Trailing comma
];
// ❌ WRONG - No trailing comma
const styles = {
container: { p: 2 },
header: { mb: 1 } // Missing comma
};
```
---
## Common Style Patterns
### Flexbox Layout
```typescript
const styles = {
flexRow: {
display: 'flex',
flexDirection: 'row',
alignItems: 'center',
gap: 2,
},
flexColumn: {
display: 'flex',
flexDirection: 'column',
gap: 1,
},
spaceBetween: {
display: 'flex',
justifyContent: 'space-between',
alignItems: 'center',
},
};
```
### Spacing
```typescript
// Padding
p: 2 // All sides
px: 2 // Horizontal (left + right)
py: 2 // Vertical (top + bottom)
pt: 2, pr: 1 // Specific sides
// Margin
m: 2, mx: 2, my: 2, mt: 2, mr: 1
// Units: 1 = 8px (theme.spacing(1))
p: 2 // = 16px
p: 0.5 // = 4px
```
### Positioning
```typescript
const styles = {
relative: {
position: 'relative',
},
absolute: {
position: 'absolute',
top: 0,
right: 0,
},
sticky: {
position: 'sticky',
top: 0,
zIndex: 1000,
},
};
```
---
## Summary
**Styling Checklist:**
- ✅ Use `sx` prop for MUI styling
- ✅ Type-safe with `SxProps<Theme>`
- ✅ <100 lines: inline; >100 lines: separate file
- ✅ MUI v7 Grid: `size={{ xs: 12 }}`
- ✅ 4 space indentation
- ✅ Single quotes
- ✅ Trailing commas
- ❌ No makeStyles or styled()
**See Also:**
- [component-patterns.md](component-patterns.md) - Component structure
- [complete-examples.md](complete-examples.md) - Full styling examples