[Home](./index.md) > [puppeteer](./puppeteer.md) > [Protocol](./puppeteer.protocol.md) > [Animation](./puppeteer.protocol.animation.md) > [Animation](./puppeteer.protocol.animation.animation.md) > [cssId](./puppeteer.protocol.animation.animation.cssid.md) ## Protocol.Animation.Animation.cssId property A unique ID for `Animation` representing the sources that triggered this CSS animation/transition. Signature: ```typescript cssId?: string; ```