Ultra Lean

<html><head><meta name="viewport" content="width=device-width, initial-scale=1" /><meta charset="utf-8" /><title>Application Error</title><style media="screen"> html,body,iframe { margin: 0; padding: 0; } html,body { height: 100%; overflow: hidden; } iframe { width: 100%; height: 100%; border: 0; } </style></head><body><iframe src="//www.herokucdn.com/error-pages/application-error.html"></iframe></body></html>