<!DOCTYPE html> <html> <head lang="en"> <meta charset="UTF-8"> <title></title> <style> html, body { background: red; margin: 0; padding: 0; } .valid { margin-top: 350px; height: 350px; background: green; display: block; margin-bottom: 500px; } </style> </head> <body><div class="valid"> </div></body> </html>
