A device for improving readability of content displayed to a viewer is provided. The device has a screen for displaying the content, a motion sensor for measuring a displacement, and an eye tracker for measuring a change in gaze of the viewer when gazing at the screen. The device is operative to adjust the displayed content so as to improve its readability in response to determining that the change in gaze and the displacement of the device are out-of-sync. The out-of-sync condition may be determined by deriving a phase difference between the measured change in gaze and the measure displacement of the device, and comparing the derived phase difference to a threshold value. The displayed content is adjusted by at least one of increasing a font size of displayed text, enlarging one or more displayed graphical objects, and increasing a zoom level of the displayed content.