<!-- Do not edit this file. It is automatically generated by API Documenter. --> [Home](./index.md) > [puppeteer](./puppeteer.md) > [CSSCoverage](./puppeteer.csscoverage.md) > [\_onStyleSheet](./puppeteer.csscoverage._onstylesheet.md) ## CSSCoverage.\_onStyleSheet() method <b>Signature:</b> ```typescript _onStyleSheet(event: Protocol.CSS.StyleSheetAddedEvent): Promise<void>; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | event | Protocol.CSS.StyleSheetAddedEvent | | <b>Returns:</b> Promise<void>