data-v-xxxxxxxx

The optional scoped attribute automatically scopes this CSS to your component by adding a unique attribute (such as data-v-21e5b78) to elements and compiling .list-container:hover to something like .list-container[data-v-21e5b78]:hover.

Lastly, the styling in Vue’s single-file components is very flexible. Through vue-loader, you can use any preprocessor, post-processor, and even deep integration with CSS Modules – all within the <style> element.

参考 scoped-css

Scoped CSS | Vue Loadervue-loader.vuejs.org