> For the complete documentation index, see [llms.txt](https://setka.gitbook.io/help-center/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://setka.gitbook.io/help-center/content-design-system-manager/components/creating-components-with-html-and-css/css-in-components.md).

# CSS in components

Components use either custom CSS classes or internal classes defined by the [Setka style](/help-center/content-design-system-manager/creating-and-editing-styles.md) itself.

## Custom CSS

The component can contain custom classes. Check the **Custom CSS for component** box on the component page to add some CSS rules. The code field for the corresponding CSS will open below. These rules are only applied to the component itself:

![Screenshot of the Setka interface: Editing the component's Custom CSS](/files/-MYFo6xiRQYFDMquT0IO)

## Internal classes

[CDSM](/help-center/content-design-system-manager/creating-and-editing-styles.md) generates these classes automatically, for each [text format](/help-center/content-design-system-manager/text-formats-and-fonts.md), [divider](/help-center/content-design-system-manager/dividers.md), [button](/help-center/setka-post-editor/buttons.md), etc. Follow [this guide](/help-center/content-design-system-manager/editing-default-elements-with-custom-css.md#step-1-find-out-the-element-class) to find the class of the standard Setka element.

Internal classes are used to identify which text format, divider or button is used in the component. E.g. if you need to use one exact header, specify its class in the component code:

```markup
<h2 class="stk-theme_3883__style_large_header">
```

Here, `stk-theme_3883__style_large_header` identifies the "Large header" text format of some style.