The viewport is set incorrectly when the viewport meta tag is specified with initial-scale = 1 or width=device-width, and the page contains an element (e.g. div tag) that is wider than the desired viewport's boundary. For example: <html> <head> <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0"/> </head> <body style="border: 2px solid red;">