For the 'colour-change' logo, we take a PNG image with a transparent shape knocked out, and animate the background colour.
Here we have used CSS animations together with the 'border' property to create a 'loading' spinner. You could use Modernizr to replace the spinner with a GIF in older browsers, or just leave it as a static icon.
By playing around with CSS3 animations and properties such as 'box-shadow', we can make buttons (or indeed any other element) display a cool pulsating-glow effect, which will degrade gracefully in older browsers.
The relative position of the box has also been animated to create a 'shakey' effect for when the form is incorrectly filled-in or a password is incorrect. Click on the ‘submit’ button to reload the page and watch the animation play.