Is there any CSS hot reload solution for the Web components?

There is no out-of-box solution for HMR with Web Components in General. It really depends on how you are using Web Components. Are you relying on just Custom Elements and using CSS-in-JS with it or fully using ShadowDOM with encapsulated styles and the underlying framework to declare those styles.

You can consider building your own HMR driver. To do this, you need all the three things in order for enable HMR - the bundler (assuming Webpack already has it), the server (webpack's dev server or middleware) and your own application.

In you own application, you would add the driver as:

// RUN SOME BOOSTRAPPING CODE

// HMR interface
if (module.hot) {
  // Capture hot update for a particular module
  module.hot.accept("./style.css", () => {
    // Logic to remove old stylesheet
  });
}

If you look at the above code, you can notice that it is almost impossible to change StyleSheet if it is defined within the shadow root for each component. If you have some global CSS which gets added to top Document then it simpler to implement HMR by manipulating StyleSheet objects from the javascript. At least, you will get partial HMR. For other activities, you can fall back to automatic full page refresh.