The cascade is a fundamental feature of CSS. It is an algorithm defining how to combine properties values originating from different sources. It lies at the core of CSS as stressed by its name: Cascading Style Sheets.
Some CSS properties can be animated, that is can change in a smooth way when its value change, either when used by CSS Animations or CSS Transitions.
A CSS layout mode, sometimes abbreviated as layout, is an algorithm determining the position and the size of boxes based on the way they interact with their sibling and ancestor boxes. There are several of them:
The resolved value of a CSS property is the value returned by getComputedStyle(). For most properties, it is the computed value, but for a few legacy properties (including width and height), it is instead the used value. See the specification link below for more per-property details.
CSS offers a number of powerful features that can be tricky to use, or have a number of parameters, so that it's helpful to be able to visualize them while you work on them. This page offers links to a number of useful tools that will help you build the CSS to style your content using these features.
The background-blend-mode CSS property describes how the element's background images should blend with each other and the element's background color. 
The isolation CSS property defines if the element must create a new stacking context.
The mix-blend-mode CSS property describes how an element's content should blend with the content of the element's direct parent and the element's background.
An at-rule is a CSS statement beginning with an at sign, '@' (U+0040 COMMERCIAL AT), followed by an identifier and includes everything up to the next semi-colon, ';' (U+003B SEMICOLON), or the next CSS block, whichever comes first.
The content CSS property is used with the ::before and ::after pseudo-elements to generate content in an element. Objects inserted using the content property are anonymous replaced elements.
CSS Columns is a module of CSS that defines a multi-column layout, allowing to express how content should flow between columns and how gaps and rules are handled.
When a URL points at a specific piece of a document, it can be difficult to ascertain. Find out how you can use some simple CSS to draw attention to the target of a URL and improve the user's experience.
CSS Text is a module of CSS that defines how to perform text manipulation, like line breaking, justification and alignment, white space handling, and text transformation.
CSS3 is the latest evolution of the Cascading Style Sheets language and aims at extending CSS2.1. It brings a lot of long-awaited novelties, like rounded corners, shadows, gradients, transitions or animations, as well as new layouts like multi-columns, flexible box or grid layouts. Experimental parts are vendor-prefixed and should either be avoided in production environments, or used with extreme caution as both their syntax and semantics can change in the future.
Set the direction CSS property to match the direction of the text: rtl for languages written from right-to-left (like Hebrew or Arabic) text and ltr for other scripts. This is typically done as part of the document (e.g., using the dir attribute in HTML) rather than through direct use of CSS.
The font-smooth CSS property controls the application of anti-aliasing when fonts are rendered.
The height CSS property specifies the height of the content area of an element. The content area is inside the padding, border, and margin of the element.
The ime-mode CSS property controls the state of the input method editor for text fields. According to the spec: