# Introduction

The SDK provides default CSS, which can be overridden by the integrators.

## Importing the stylesheet

If you're using SCSS:

```scss
@import "~stream-chat-react/dist/scss/v2/index.scss";
```

If you're using CSS:

```css
@import "~stream-chat-react/dist/css/v2/index.css";
```

## Customization

Our theming system has various customization options allowing for both smaller and large-scale UI changes. This document guides you through the different customization options.

### CSS variables

CSS variables are the easiest way to customize the theme. The variables are organized into two layers:

- global
- component

#### Global variables

You can use global variables to apply changes to the whole chat UI (as opposed to changing the design of individual components).

<admonition type="info">

The [full list of global variables](/chat/docs/sdk/react/theming/global-variables/) can be found in our global variables guide.

</admonition>

Here is the default chat UI:

![Default Stream Chat React UI](@chat-sdk/react/v13-latest/_assets/stream-chat-css-chat-ui-screenshot.png)

Here is how you can customize global variables:

```scss
@import "~stream-chat-react/dist/scss/v2/index.scss";
```

```scss
.str-chat {
  --str-chat__primary-color: #009688;
  --str-chat__active-primary-color: #004d40;
  --str-chat__surface-color: #f5f5f5;
  --str-chat__secondary-surface-color: #fafafa;
  --str-chat__primary-surface-color: #e0f2f1;
  --str-chat__primary-surface-color-low-emphasis: #edf7f7;
  --str-chat__border-radius-circle: 6px;
}
```

Here is the result:

![Stream Chat Css Chat Ui Theme Customization](@chat-sdk/react/v13-latest/_assets/stream-chat-css-chat-ui-theme-customization-screenshot.png)

<admonition type="note">

The `str-chat` class is applied to the [`ChannelList`](/chat/docs/sdk/react/components/core-components/channel_list/) and [`Channel`](/chat/docs/sdk/react/components/core-components/channel/) components, all CSS variables are declared on this level.

</admonition>

#### Component variables

<Admonition type="info">

You can use component layer variables to change the design of individual components. The [full list of component variables](/chat/docs/sdk/react/theming/component-variables/) can be found in our component variables guide.

</admonition>

In the above example we set the avatar background color by setting the `--str-chat__primary-color` variable which also sets the color of other UI elements. If we want to change the background color only for the avatar component we can use the `--str-chat__avatar-background-color` variable:

```scss
.str-chat {
  --str-chat__primary-color: #009688;
  --str-chat__active-primary-color: #004d40;
  --str-chat__surface-color: #f5f5f5;
  --str-chat__secondary-surface-color: #fafafa;
  --str-chat__primary-surface-color: #e0f2f1;
  --str-chat__primary-surface-color-low-emphasis: #edf7f7;
  --str-chat__border-radius-circle: 6px;
  --str-chat__avatar-background-color: #bf360c; // Only changes the background color of the avatar component
}
```

Here is the result:

![Stream Chat React UI With Custom Avatar Color](@chat-sdk/react/v13-latest/_assets/stream-chat-css-custom-avatar-color-screenshot.png)

Component variables don't inherit. Let's see an example of this.

Here is the message component without custom color:

![Stream Chat Css Message Color](@chat-sdk/react/v13-latest/_assets/stream-chat-css-message-color-screenshot.png)

Setting custom text color inside message bubble:

```scss
.str-chat {
  --str-chat__primary-color: #009688;
  --str-chat__active-primary-color: #004d40;
  --str-chat__surface-color: #f5f5f5;
  --str-chat__secondary-surface-color: #fafafa;
  --str-chat__primary-surface-color: #e0f2f1;
  --str-chat__primary-surface-color-low-emphasis: #edf7f7;
  --str-chat__border-radius-circle: 6px;
  --str-chat__avatar-background-color: #bf360c;
  --str-chat__message-bubble-color: #00695c; // Custom text color only for the message bubble
}
```

![Stream Chat React UI With Custom Message](@chat-sdk/react/v13-latest/_assets/stream-chat-css-message-color-customization-screenshot.png)

We can see that setting the text color of the message bubble won't change the color of the link attachments.

To solve this we also have to set the text color for the link attachment component:

```scss
.str-chat {
  --str-chat__primary-color: #009688;
  --str-chat__active-primary-color: #004d40;
  --str-chat__surface-color: #f5f5f5;
  --str-chat__secondary-surface-color: #fafafa;
  --str-chat__primary-surface-color: #e0f2f1;
  --str-chat__primary-surface-color-low-emphasis: #edf7f7;
  --str-chat__border-radius-circle: 6px;
  --str-chat__avatar-background-color: #bf360c;
  --str-chat__message-bubble-color: #00695c;
  --str-chat__card-attachment-color: #00695c; // Setting text color of link attachments
}
```

![Stream Chat React UI With Matching Text Color](@chat-sdk/react/v13-latest/_assets/stream-chat-css-message-color-customization2-screenshot.png)

### CSS overrides

If you'd like to add customizations that are not supported by CSS variables, you can override parts of the default CSS:

```scss
@import "~stream-chat-react/dist/scss/v2/index.scss";
```

```scss
// Provide your overrides after the stream-chat-angular stylesheet imports
.str-chat__channel-preview-messenger--last-message {
  font-weight: 500;
}
```

Just make sure that you add the customization rules after the stylesheet import.

If you're using SCSS it's also possible to import component stylesheets separately (instead of our bundled stylesheet):

```scss
// Use default theme for channel list and channel preview components
@import "~stream-chat-react/dist/scss/v2/ChannelList/ChannelList-layout.scss";
@import "~stream-chat-react/dist/scss/v2/ChannelList/ChannelList-theme.scss";
@import "~stream-chat-react/dist/scss/v2/ChannelPreview/ChannelPreview-layout.scss";
@import "~stream-chat-react/dist/scss/v2/ChannelPreview/ChannelPreview-theme.scss";
```

```scss
.str-chat__avatar {
  // Custom CSS for avatar component
}
```

### Apply your own look and feel

<admonition type="info">

If you want to create a truly custom look and feel, it can be exhausting to override the default styling. In that case, it's possible only to apply layout rules from the default theme.

</admonition>

Here is how you can import the layout stylesheet:

```scss
@import "~stream-chat-react/dist/scss/v2/index.layout.scss";
```

or if you're using CSS:

```css
@import "~stream-chat-react/dist/css/v2/index.layout.css";
```

![Stream Chat React layout Displaying Unstyled Chat Structure Without Colors, Fonts, Borders, or Shadows](@chat-sdk/react/v13-latest/_assets/stream-chat-css-chat-ui-layout-screenshot.png)

The result will be a minimalistic UI without

- coloring
- fonts
- borders
- shadows

Please note that if you're only using the layout rules, you can only use the layout CSS variables.

## Dark and light themes

> The default theme has dark and light variants.

Here is how you can switch between the different themes:

```tsx
<Chat client={client} theme="str-chat__theme-dark">
  {/* ... */}
</Chat>
```

or only to a specific component (`Channel` or/and `ChannelList`):

<admonition type="note">

Using the `customClasses` approach for either of the components will override default class names. Don't forget to add those to your theme class names (as defined in the snippet) for the styling to work properly.

</admonition>

```tsx
<Chat
  client={client}
  customClasses={{
    channelList: "str-chat__theme-dark str-chat__channel-list",
    channel: "str-chat__theme-light str-chat__channel",
  }}
>
  {/* ... */}
</Chat>
```

Here is what the dark theme looks like:

![Stream Chat React UI in Dark Theme](@chat-sdk/react/v13-latest/_assets/stream-chat-css-dark-ui-screenshot.png)

<admonition type="note">

The `str-chat__theme-dark`/`str-chat__theme-light` class is applied to the [ChannelList](/chat/docs/sdk/react/components/core-components/channel_list/) and [Channel](/chat/docs/sdk/react/components/core-components/channel/) components, these classes are responsible for switching between the dark and light theme color combinations.

</admonition>

Here is how you can provide different color configurations for the dark and light themes:

```scss
@import "~stream-chat-react/dist/scss/v2/index.scss";
```

```scss
.str-chat {
  --str-chat__border-radius-circle: 6px;
}

.str-chat__theme-light {
  --str-chat__primary-color: #009688;
  --str-chat__active-primary-color: #004d40;
  --str-chat__surface-color: #f5f5f5;
  --str-chat__secondary-surface-color: #fafafa;
  --str-chat__primary-surface-color: #e0f2f1;
  --str-chat__primary-surface-color-low-emphasis: #edf7f7;
  --str-chat__avatar-background-color: #bf360c;
}

.str-chat__theme-dark {
  --str-chat__primary-color: #26a69a;
  --str-chat__active-primary-color: #00796b;
  --str-chat__surface-color: #424242;
  --str-chat__secondary-surface-color: #212121;
  --str-chat__primary-surface-color: #00695c;
  --str-chat__primary-surface-color-low-emphasis: #004d40;
  --str-chat__avatar-background-color: #ff7043;
}
```

Here is the custom dark theme:

![Stream Chat React UI With a Custom Dark Theme](@chat-sdk/react/v13-latest/_assets/stream-chat-css-custom-dark-theme-screenshot.png)

### Creating your own theme

It's possible to extend the existing themes with your own themes.

> Here is an example creating 'round' and 'square' themes:

```scss
@import "~stream-chat-react/dist/scss/v2/index.scss";
```

```scss
// Make sure to use the proper naming convention: str-chat__theme-<your theme>
.str-chat__theme-round {
  // You can use the predefined theme and component layer variables
  --str-chat__border-radius-circle: 999px;
}

.str-chat__theme-square {
  --str-chat__border-radius-circle: 6px;
}
```

```tsx
<Chat client={client} theme="str-chat__theme-square">
  {/* ... */}
</Chat>
```

or only to a specific component (`Channel` or/and `ChannelList`):

<admonition type="note">

Using the `customClasses` approach for either of the components will override default class names. Don't forget to add those to your theme class names (as defined in the snippet) for the styling to work properly.

</admonition>

```tsx
<Chat
  client={client}
  customClasses={{
    channelList: "str-chat__theme-square str-chat__channel-list",
    channel: "str-chat__theme-round str-chat__channel",
  }}
>
  {/* ... */}
</Chat>
```

![Stream Chat React UI With a Square Theme](@chat-sdk/react/v13-latest/_assets/stream-chat-css-square-theme-screenshot.png)

## RTL support

The layout was built with RTL support in mind. You can use the RTL layout by providing the `dir` attribute in your HTML:

```html
<html dir="rtl">
  <!-- ... -->
</html>
```

Here is the result:

![Stream Chat React UI Rendered in Right-to-Left Layout](@chat-sdk/react/v13-latest/_assets/stream-chat-css-rtl-layout-screenshot.png)

---

This page was last updated at 2025-08-15T14:16:05.892Z.

For the most recent version of this documentation, visit [https://getstream.io/chat/docs/sdk/react/theming/themingv2/](https://getstream.io/chat/docs/sdk/react/theming/themingv2/).