An issue occurs where the map does not appear

Below is an example of placing a dot on the Earth. A few days ago, the map came out normally, but suddenly the map doesn’t come out.

CesiumJS Basic Example #cesiumContainer { width: 100%; height: 100%; margin: 0; padding: 0; overflow: hidden; }

Why is that so?
Thanky you in advanced

It was a browser cache issue. After clearing the cache, the map appears normally. thank you