That looks like your browser is failing to load the css for the page. Does it clear up when you force a refresh of the page?
If not, you can get more information about the error by opening up the developer console in your browser. The hotkey is Option-Command-I or Alt-Control-I depending on your OS, if I recall correctly. Then open the "network" tab and refresh. The line for the css file should be red.
Are you seeing this error with a full install including Apache or Nginx? The server logs for either of those might have clues for why the css is failing too. When you install in that way, the web server (i.e. Apache or Nginx) are serving the css directly.