mo-css | A non-component-level pure css framework

Your project is missing the lumo-css-framework npm dependency. There are two ways you can add it:

1. npm install --save lumo-css-framework. This will store the dependency in package.json which contains a list of all npm dependencies needed in the project. It is academically wrong to say that package.json is auto generated as what Vaadin really does it populates package.json with whatever the Java side (mainly components) define as their npm dependencies. Any other dependency defined in package.json is left alone.

2. Annotate any Java class in the project with @NpmDependency(value="lumo-css-framework", version="^3.0.11"). This annotation will be used by Vaadin when figuring out what npm dependencies are needed for the project and then package.json will be updated based on the annotation.