Because VSys Anywhere runs in a browser, the details of how things are displayed are left up to your computer's browser and operating system. VSys uses HTML5 and CSS to tell the browser how VSys would like something shown, the browser then interprets that based on your device, screen size, orientation and other settings that you may have made.
In most web browsers, clicking Ctrl + will zoom in using the keyboard; Ctrl - will zoom out. On touch screen devices, "pinch to zoom".