<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style type="text/css"> *{ margin: 0; padding: 0; } html,body{ width: 100%; height: 100%; } .c1{ width: 90%; height: 90%; } </style> </head> <body> <div class="c1"></div> </body> </html>