The Can I Use site is a thorough and extremely helpful resource site for web designers. It is a database of CSS and HTML elements/properties that tells you how widely supported each item is. Over time, old properties are retired and new ones arise. Browsers are not all consistent with when they update their software to support each of these items. Because of this, it's important to keep up to date on which browsers will show this coding as expected. You can use this site to easily search for a property or element and see which browser versions do support it.
CSS Transitions - This property is used to create various transition/animation effects one or many properties on an element. According to Can I Use, this is a widely supported item, getting a score of 98.41%. Only the oldest versions of IE, Firefox, and Opera do not support this.
I found this property interseting after seeing it used for so many things in my courses so far. Using a transition is a simple way to add a bit of movement and upscaled design to a page without using a crazy amount of code or making special animated graphics.
Calc - The calc property is used to make calculations within a CSS value. It is also widely supported, with a score of 93.24%. The oldest versions of IE, Firefox, Chrome, Safari and Opera do not support it but they are also note as widely used. All versions of IE only partly support it. There are issues with it not working properly in many instances, including the background-position value within even newer versions of IE.
I found this property interesting because of the wide amount of ways it can be used to customize width and placement of things. It's really powerful and can open up a lot of possibilities in coding by using it.
The Can I Use site is an amazing resource as a web developer. It is definitely a site to consult when you hear about a new CSS or HTML element or property. New things can be great to try out, but if they only work in a few select, newest browsers, you need to determine if using them will affect the how the site looks & behaves on other browsers (or previous versions).