.left { height: 100vh; width: 50%; background-color: grey; float: left; } .right { height: 100vh; width: 50%; background-color: red; float: right; }
<!DOCTYPE html> <html> <head> <title>100% height</title> <style> html, body { height: 100%; margin: 0; } .container { height: 100%; background: #000; /* to see the effect */ } </style> </head> <body> <div class="container"></div> </body> </html>