Tryit Editor v1.8

Source Code:
<!DOCTYPE html> <html> <head> <style> p:first-child { background-color:yellow; } </style> </head> <body> <p>This paragraph is the first child of its parent (body).</p> <h1>Welcome to My Homepage</h1> <p>This paragraph is not the first child of its parent.</p> <div> <p>This paragraph is the first child of its parent (div).</p> <p>This paragraph is not the first child of its parent.</p> </div> <p><b>Note:</b> For :first-child to work in IE8 and earlier, a DOCTYPE must be declared.</p> </body> </html>
Result:
W3Schools.com - Try it yourself