Loading.io's CSS spinner uses CSS Animation to create Loading and Preloading animations. There are supported by all modern browsers such as Google Chrome and Mozilla Firefox.
Please read the documentation (in the plugin), the Bubble Editor and the example at the Service URL:
Editor, documentation, step-by-step and example:
https://bubble.io/page?type=page&name=css-loader&id=bubble-essential-plugins&tab=tabs-1Demo page:
https://bubble-essential-plugins.bubbleapps.io/version-test/css-loader?debug_mode=trueCredits
https://loading.io/css/