Tryit Editor v1.8

Source Code:
<!DOCTYPE html> <html> <head> <style> h1 {font-size:2.5em;} /* 40px/16=2.5em */ h2 {font-size:1.875em;} /* 30px/16=1.875em */ p {font-size:0.875em;} /* 14px/16=0.875em */ </style> </head> <body> <h1>This is heading 1</h1> <h2>This is heading 2</h2> <p>This is a paragraph.</p> <p>Specifying the font-size in em allows all major browsers to resize the text. Unfortunately, there is still a problem with older versions of IE. When resizing the text, it becomes larger/smaller than it should. </p> </body> </html>
Result:
W3Schools.com - Try it yourself