When the element has empty content, you might want to display some text to idicate the compoent is loading...
<!DOCTYPE html> <html> <head> <style> p:empty { width: 100px; height: 20px; background: #ff0000; } p:empty:after { content: "Loading..., please wait" } </style> </head> <body> <p></p> <p>A paragraph.</p> <p>Another paragraph.</p> </body> </html>