What forces layout/reflow: a comprehensive list by Paul Irish

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

CSS custom properties are not variables

A screenshot of the CSS spec highlighting the distinction between a custom property and a variable.

CSS custom properties are commonly known as CSS variables, and judging by the main web development blogs and resources, most people likely use the terms “custom property” and “variable” interchangeably[.]


The reason for this could be that the CSS spec itself uses both terms. ”Custom properties” and “variables” both appear in the spec’s text dozens of times and even in the spec’s own title (“CSS Custom Properties for Cascading Variables”).

However, the spec distinguishes the two terms: A custom property is not a variable, but it defines a variable. Any property can use variables with the var() function whose values are defined by their associated custom properties.


This distinction is useful because it allows us to talk about “variables with fallback values” (a custom property like any other property cannot have a fallback value) and “properties using variables” (a property cannot use a custom property) […] as well as “declaring a custom property on an element” (a variable isn’t declared but assigned to a property) and “the computed value of a custom property” (a variable doesn’t have a computed value but draws from the computed value of its associated custom property).


Can I use… is an invaluable resource that we all (hopefully) use on a regular basis, but what if you have an existing codebase that you want to evaluate for browser support? You could go through it manually, but that could be a lot of work. Thankfully, someone has put together an app and a Node.js module that can crawl your CSS and list what will break in what browser.

CSS Motion Path

Motion Path is a CSS module that allows authors to animate any graphical object along a custom path.

The idea is that when you want to animate an element moving along a path, you previously only had animating translation, position, etc. at your disposal, which wasn’t ideal and only allowed for simple movements. With offset-path you can define a specific path of any shape you want. You then animate it along that path by animating offset-distance, and can choose to rotate it at any point using offset-rotate.

Code language: CSS

#motion-demo {
  offset-path: path('M20,20 C20,100 200,0 200,100');
  animation: move 3000ms infinite alternate ease-in-out;
  width: 40px;
  height: 40px;
  background: cyan;
@keyframes move {
  0% {
    offset-distance: 0%;
  100% {
    offset-distance: 100%;

Brutalist Web Design

The term brutalism is often associated with Brutalist Architecture, however it can apply to other forms of construction, such as web design.


The term brutalism is derived from the French béton brut, meaning “raw concrete”. Although most brutalist buildings are made from concrete, we’re more interested in the term raw. Concrete brutalist buildings often reflect back the forms used to make them, and their overall design tends to adhere to the concept of truth to materials.

A website’s materials aren’t HTML tags, CSS, or JavaScript code. Rather, they are its content and the context in which it’s consumed. A website is for a visitor, using a browser, running on a computer [or mobile device] to read, watch, listen, or perhaps to interact. A website that embraces Brutalist Web Design is raw in its focus on content, and prioritization of the website visitor.

Brutalist Web Design is honest about what a website is and what it isn’t. A website is not a magazine, though it might have magazine-like articles. A website is not an application, although you might use it to purchase products or interact with other people. A website is not a database, although it might be driven by one.

They list the following principles:

The Perfect Paragraph

Walking down an aisle in a library, I no more than glance at the vast majority of books shelved on either side of me. Only a madman would suggest that my disregard of these books should sanction their pages being torn out. Nonetheless, because research has shown that visitors don’t read the average Web page in full, and because the “success” of a page is more easily measured by user action than cognition, we are often encouraged to marginalize our writing in favor of visual signifiers or action cues.

Sure, most people will “bounce” your content, but if you really have something to say, don’t alienate the people who are willing to give your writing a chance. Good typography does justice to your words, and good wording does justice to your ideas. If readers are comfortable reading your type, then they will more likely be comfortable with what you are writing about.