Preface

Less (Leaner CSS) is a preprocessor, which means Less code compiles into static CSS code. Less changes the way you write and maintain your CSS code; the final CSS code will be the same, but better organized in many situations.

In your hands is the Less Web Development Essentials, Second Edition book. Since the successful first edition of this book, Less has been improved still further. This book has been updated for the all new features that come with the release of Less Version 2. The Less Version 2 release not only has many improvements, but has also introduced the possibility to use and write Less plugins. Less plugins will enable you to customize Less for your own unique needs.

In the semantic sense, valid CSS code is also valid Less code. Less tries to stay as close as possible to the declarative nature of CSS. Coding Less is intuitive and easy to learn for those who are already familiar with CSS.

Since the introduction of CSS3 in 2012, the role of CSS in modern web development has become more and more important. Nowadays, CSS3 is not only used to style your HTML documents, but also plays an important role in the responsibility of your designs. Last but not least, CSS3 extends CSS with features such as animations and transitions.

Writing correct functional CSS code will be the first thing—and keeping this code readable—working on all major browsers will be the second. CSS files grow and become untidy during the development and maintenance processes. CSS also doesn't have the ability to modify existing values or reuse common styles. Also, doing math or defining variables is not possible in CSS. This is where Less comes into the frame.

Less is a dynamic style sheet language designed by Alexis Sellier. Started in 2010 and now maintained and extended by the Less core team, it helps you make your CSS code maintainable, reusable, and also prevents code duplications. It also enables you to write your CSS code DRY (Do not Repeat Yourself), extending CSS syntax with variables, mixins, functions, and many other techniques. Less ensures that the CSS language is more maintainable, themable, and extendable.

In this book, you will learn to write, compile, and understand Less. We will help you to perform faster and more cost effective web development. You will get practical tips to integrate Less into your current and new projects. After reading this book, you will write clear and readable CSS3 with Less. Instead of spending your time debugging your complex CSS code for a specific device or browser, you can pay more attention to your real-design tasks.

Your clients will be happy with your advanced and stable designs. Development and maintenance time, along with expenditure, will decrease.

Also, other projects know the power of Less. Projects such as Twitter Bootstrap and the WordPress Roots theme rely on Less. These projects build clear and extendable frameworks with Less.

Less is open source and licensed under Apache License. The source code of Less is maintained on GitHub. Everybody will be allowed to contribute to it. You can use Less free of charge.