Tryit Editor v1.8

Source Code:
<!DOCTYPE html> <html> <head> <style> p:first-line { background-color:yellow; } </style> </head> <body> <h1>WWF's Mission Statement</h1> <p>To stop the degradation of the planet's natural environment and to build a future in which humans live in harmony with nature, by; conserving the world's biological diversity, ensuring that the use of renewable natural resources is sustainable, and promoting the reduction of pollution and wasteful consumption.</p> </body> </html>
Result:
W3Schools.com - Try it yourself