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# CSS customization

Bitmovin UI renders playback controls and overlays as DOM elements with predefined CSS class names (for example, `.bmpui-seekbar` and `.bmpui-ui-uicontainer`).

Using CSS overrides lets you:

* Customize colors, fonts, and sizes

* Align playback controls with your brand

* Improve accessibility and responsive behavior

* Change visual behavior at runtime

## Example: larger seekbar and branded colors

```css
/* Big seekbar font size */
.bmpui-seekbar.bigseek > * {
  font-size: 3em;
}

/* Seekbar backdrop colors */
.bmpui-seekbar-backdrop.green {
  background-color: #034728 !important;
}

```

This makes seekbar elements larger and changes the seekbar backdrop color.

## Example: base font defaults

```css
.bmpui-ui-uicontainer {
  font-family: "Roboto";
  font-size: 16px;
}

```

This sets a consistent font baseline across UI elements.
You can also update label and button text styling to signal UI states such as on/off transitions.

## Related references

UIConfig: Bitmovin UIConfig interface

* Bitmovin UI modules: Bitmovin UI modules

* UI factory variants: Bitmovin UI factory docs

* CSS class reference: Bitmovin CSS class reference