This tutorial shows how to place a map on a page and have it "flow" with the other content. Notice that we had to add a container around the MapContainer. This container will provide the dimensions needed (width and height) for the browser because as soon as we position the elements inside the MapContainer using "absolute" positions, the browser thinks the MapContainer has shrunk to 0 pixels.

This approach does require a web server but it does not require you to modify the GeoJSON files. Try this with different types of shapefiles including points and polylines.