There is a media query that checks the pixel density of the device and based on that, shows the default logo. This is why you won’t see it when you just resize your browser.
http://budeiriarchitects.com/wp-content/themes/invictus-new/css/retina.css
You can debug it by using Chrome’s built-in iPhone emulator, which also emulates the iPhone pixel density too. When you have your inspector open, click on the little phone icon in the top left of the inspector panel.
