The Cup sizing and physics are tuned for an intended browser source window height of 1080 pixels. Generally speaking, the closer your Cup browser source window height is to 1080 the better the physics and appearance will be.
Cup browser source window heights greater than 1080 pixels will result in larger bits, a larger cup, and more vertical spacing between text lines when multiple cheer messages are on screen. Cup browser source window heights lower than 1080 pixels will scale down the size of the bits and the cup while text will not be scaled down to preserve readability.
For users that really want to use a very low window height or if you still can't find a size that suits you, then you can tinker with the scale variable by using the scale argument in your cup URL by adding “?scale=1” to the end of your cup URL. Changing the numeric value and refreshing page will scale the visualization environment, physics may be affected with altered scale values.