Tryit Editor v1.8

Source Code:
<!DOCTYPE html> <html> <head> <style> body {font-size:100%;} h1 {font-size:2.5em;} h2 {font-size:1.875em;} p {font-size: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 percent and em displays the same size in all major browsers, and allows all browsers to resize the text!</p> </body> </html>
Result:
W3Schools.com - Try it yourself