diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index 8a5d644..e73eaff 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -81,3 +81,13 @@ node dist/src/server.js 2>&1 | tee server.log
 - `app/src/browserEventBus.ts` - Socket.io client
 - `app/src/components/BrowserAuthWrapper.tsx` - Auth dialog
 - `app/src/index.tsx` - React entry, theme providers
+
+## Styling Conventions
+
+When modifying or creating UI components, follow the styling patterns documented in <a>STYLING.md</a>.
+
+**Key points for AI agents:**
+- Use Material-UI (MUI) v7 components with `withStyles` HOC for styling
+- Access theme colors via `theme.palette.*`, spacing via `theme.spacing()`, typography via `theme.typography.*`
+- Support both light and dark modes with theme-conditional styling
+- Import Material-UI colors: `import { blueGrey, amber, green, red } from '@mui/material/colors'`
diff --git a/Readme.md b/Readme.md
index 59218d4..0751c8e 100644
--- a/Readme.md
+++ b/Readme.md
@@ -99,6 +99,8 @@ yarn dev:server
 
 The `app` directory contains all the rendering logic, the `backend` directory currently contains the models, tests, connection management, `src` contains all the electron bindings. [mqttjs](https://github.com/mqttjs/MQTT.js) is used to facilitate communication to MQTT brokers.
 
+For information on styling conventions and visual design patterns, see [STYLING.md](STYLING.md).
+
 ## Automated Tests
 
 MQTT Explorer uses multiple test suites to ensure reliability and quality:
diff --git a/STYLING.md b/STYLING.md
new file mode 100644
index 0000000..90cc60a
--- /dev/null
+++ b/STYLING.md
@@ -0,0 +1,212 @@
+# MQTT Explorer Styling Conventions
+
+This document outlines the styling conventions used in MQTT Explorer for visual consistency and maintainable code.
+
+## UI Framework
+
+Material-UI (MUI) v7 with JSS styling via `withStyles` HOC.
+
+**Stack:**
+- `@mui/material` (v7) - Core components and theming
+- `@mui/icons-material` (v7) - Icons
+- `@mui/styles` (v6) - JSS styling with `withStyles`
+- `@emotion/react` & `@emotion/styled` - CSS-in-JS foundation
+
+## Theming
+
+**Location:** `app/src/theme.ts`
+
+**Configuration:**
+- Light and dark modes supported
+- Primary color: `#335C67` (teal/blue-green)
+- Secondary: Material-UI `amber` palette
+- Base typography: `0.9rem`, `userSelect: 'none'`
+
+**Application:**
+```typescript
+<ThemeProvider theme={theme}>
+  <LegacyThemeProvider theme={theme}>
+    <App />
+  </LegacyThemeProvider>
+</ThemeProvider>
+```
+
+## Colors
+
+**Access theme colors:**
+```typescript
+backgroundColor: theme.palette.background.default
+color: theme.palette.text.primary
+borderColor: theme.palette.divider
+```
+
+**Material-UI palettes:**
+```typescript
+import { blueGrey, amber, green, red, orange } from '@mui/material/colors'
+backgroundColor: blueGrey[100]  // Light shade
+backgroundColor: blueGrey[700]  // Dark shade
+```
+
+**Theme-conditional:**
+```typescript
+const color = theme.palette.mode === 'light' ? blueGrey[300] : theme.palette.primary.main
+```
+
+**Code editor colors:** Defined in `app/src/components/Sidebar/CodeBlockColors.ts`
+
+## Typography
+
+**Variants:**
+```typescript
+<Typography variant="h6">Heading</Typography>
+<Typography variant="body1">Body text</Typography>
+<Typography variant="caption">Caption</Typography>
+```
+
+**Font sizes:**
+```typescript
+fontSize: theme.typography.pxToRem(15)
+```
+
+**Monospace:** `"12px/normal 'Monaco', 'Menlo', 'Ubuntu Mono', 'Consolas', 'source-code-pro', monospace"`
+
+## Spacing
+
+**8px grid system:**
+```typescript
+margin: theme.spacing(1)      // 8px
+padding: theme.spacing(2)     // 16px
+marginLeft: theme.spacing(1.5) // 12px (tree indentation)
+```
+
+**Border radius:**
+```typescript
+borderRadius: theme.shape.borderRadius  // 4px default
+```
+
+## Component Styling
+
+**Primary approach - withStyles HOC:**
+```typescript
+import { withStyles } from '@mui/styles'
+import { Theme } from '@mui/material/styles'
+
+const styles = (theme: Theme) => ({
+  root: {
+    backgroundColor: theme.palette.background.default,
+    padding: theme.spacing(2),
+  },
+})
+
+export default withStyles(styles)(MyComponent)
+```
+
+**Type assertions:**
+```typescript
+display: 'block' as 'block'
+whiteSpace: 'nowrap' as 'nowrap'
+overflow: 'hidden' as 'hidden'
+```
+
+**Responsive:**
+```typescript
+[theme.breakpoints.up(750)]: {
+  display: 'block',
+}
+```
+
+**sx prop (simple cases):**
+```typescript
+<Button sx={{ color: 'primary.contrastText' }}>Text</Button>
+```
+
+## Animations
+
+**CSS animations:**
+```typescript
+animation: 'updateLight 0.5s'
+```
+
+**Theme transitions:**
+```typescript
+transition: theme.transitions.create('transform', {
+  easing: theme.transitions.easing.sharp,
+  duration: theme.transitions.duration.leavingScreen,
+})
+```
+
+## Interactive States
+
+**Hover:**
+```typescript
+'&:hover': {
+  backgroundColor: theme.palette.mode === 'light' 
+    ? blueGrey[100] 
+    : theme.palette.primary.light,
+}
+```
+
+**Selection:**
+```typescript
+selected: {
+  backgroundColor: (theme.palette.mode === 'light' 
+    ? blueGrey[300] 
+    : theme.palette.primary.main) + ' !important',
+}
+```
+
+## Common Patterns
+
+**Tree nodes:**
+```typescript
+node: {
+  overflow: 'hidden',
+  textOverflow: 'ellipsis',
+  whiteSpace: 'nowrap',
+}
+subnodes: {
+  marginLeft: theme.spacing(1.5),
+}
+```
+
+**Buttons:**
+```typescript
+<Button variant="contained" color="primary">Submit</Button>
+<Button variant="outlined" color="primary">Cancel</Button>
+<Button>Learn More</Button>
+```
+
+**Icons:**
+```typescript
+<Icon fontSize="inherit" />
+<Icon style={{ fontSize: '16px' }} />
+```
+
+## Best Practices
+
+**DO:**
+✅ Use theme variables (`theme.palette.*`, `theme.spacing()`, `theme.typography.*`)
+✅ Use `withStyles` HOC for component styles
+✅ Use `theme.palette.mode` for light/dark conditional styling
+✅ Import Material-UI color palettes for extended colors
+✅ Keep styles co-located with components
+
+**DON'T:**
+❌ Hardcode colors or spacing values
+❌ Create global CSS files
+❌ Duplicate style definitions
+❌ Use inline styles for complex patterns
+
+## Resources
+
+- [Material-UI Documentation](https://mui.com/material-ui/getting-started/)
+- [Color System](https://mui.com/material-ui/customization/color/)
+- [Theming Guide](https://mui.com/material-ui/customization/theming/)
+
+**Testing:** Verify in both light/dark themes, check responsive behavior, ensure accessibility.
+
+## Related
+
+- [README.md](./Readme.md) - Project overview
+- [BROWSER_MODE.md](./BROWSER_MODE.md) - Browser mode
+- [.github/copilot-instructions.md](./.github/copilot-instructions.md) - Copilot instructions