Sources and Third-Party Libraries
Light peppered moth image: Wikimedia, 2006 (https://en.wikipedia.org/wiki/File:Biston.betularia.7200.jpg)
Dark peppered moth image: Wikimedia, 2006 (https://en.wikipedia.org/wiki/File:Biston.betularia.f.carbonaria.7209.jpg)
Sooty tree bark background: Arizona State University, 2015 (https://askabiologist.asu.edu/peppered-moths-game/assets/images/dark-forest.jpg)
Light tree bark background: Paul Sterry, n.d. (https://www.woodlandtrust.org.uk/visiting-woods/trees-woods-and-wildlife/british-trees/native-trees/common-beech/)
Moth silhouette icon: ArtsyBee on Pixabay, 2015 (https://pixabay.com/en/silhouette-drawing-outline-971333/)
Materialize CSS (https://materializecss.com, © 2019) is made available under the MIT license
jQuery (https://jquery.com/, © 2019) is made available under the MIT license