performance-checklist VS less.js

OOCSS - (Object-oriented CSS) 2. Use a preprocessor. They fill the lacking features of CSS and helps you write more readable, and smaller reusable pieces of CSS. Some popular preprocessors are: 1. Sass 2. Less 3. Stylus 3. Reduce redundancy. You are using font-weight: bold for the header, but you are also setting it for the div inside. CSS stands for Cascading Style Sheets because styles in CSS are cascading, meaning child elements will inherit styles from parents. 4. Avoid using strong and complex selectors. You are using an id, but a class would do just fine. Having strong selectors means you will have a harder time overriding them later on if needed. 5. Avoid using !important as much as possible. Only use it for utility and helper classes if you must, which need to override anything, such as hiding or displaying an element. 6. Don't use inline CSS, unless your inlining critical CSS. Instead, import styles using a link tag in your head element. (Critical CSS refers to above-the-fold content. Inlining it can help users see a properly rendered page more quicker) 7. Use semantic HTML. You are assigning a header class to a div, which could have been an h1/2/3/n element. This not only helps in terms of accessibility but can also help to improve your SEO score. 8. Use rem for typography. You are using em which cascades, meaning if you set the root element to have 12px, a main element with 2em will have the font size of 24px. If you put a div inside of it with 2em, it will have a font size of 48px, meaning that the size is duplicated. This makes it hard to track down values for deeply nested elements. Instead, use rem which stands for root em, and does not cascade. 9. Make sure your formatting is consistent. You use opening brackets both after a selector and on a new line. Tools like stylelint can help you enforce certain rules to keep your code more consistent, which helps to improve readability and maintainability. 10. Outsource your colors / sizes / spacings into variables. Everything that is bound to change can be in a configuration file to make things more flexible. You can either use CSS variables for this, or a preprocessor. 11. Nothing is written in stone, feel free to come up with your own set of rules that helps you create a more dev-friendly environment. But most importantly, keep things consistent.

LESS [ https://lesscss.org ]

Traditionally CSS lacked features such as variables, nesting, mixins, and functions. This was frustrating for Developers as it often led to CSS quickly becoming complex and cumbersome. In an attempt to make code easier and less repetitive CSS pre-processors were born. You would write CSS in the format the pre-processor understood and, at build time, you'd have some nice CSS. The most common pre-processors these days are Sass, Less, and Stylus. Any examples I give going forward will be about Sass as that's what I'm most familiar with.

In the past, you’d need to rely on pre-processors such as SaSS or Less, but not anymore… Native CSS nesting has landed on all major modern browsers.

Consider using CSS preprocessors like Sass or Less not only for better code organization but also for potential performance improvements.

Extensions of CSS: for example, Sass, Less, Tailwind, CSS Modules, to make stuff look a certain way on your own.

LiveCodes provides many of the commonly used developer tools. These include Monaco editor (that powers VS Code), Prettier, Emmet, Vim/Emacs modes, Babel, TypeScript, SCSS, Less, PostCSS, Jest and Testing Library, among others. All these tools run seamlessly in the browser without any installations or configurations. It feels like a very light-weight version of your own local development environment including the keyboard shortcuts, IntelliSense and code navigation features.

LESS

The CSS Working Group had been aware of the need for CSS variables since its inception in 1997. By the late 2000s, developers had created various workarounds like custom PHP scripts and preprocessors like Less and Sass to compensate for this deficiency.

He could do with LESS

While we may disagree whether Sass is still relevant today, Mayank's case for using Sass in 2022 sums up the many use cases for Sass/SCSS including a timeline from 2006 (Sass) to "2022+" (nesting). Nesting CSS used to one of the few good reasons left to choose Sass, SCSS (or less) in a new web project.