<!DOCTYPE html> <body style="width: 100vw; height: 100vh; margin: 0; padding: 10px 11px 12px 14px; box-sizing: border-box"> <div id="border" style="border: solid; width: 100%; height: 100%; box-sizing: border-box"> <div style="width: 100px; height: 100px; background: green"></div> </div> </body>