About CSS to LESS

Convert CSS to LESS preprocessor syntax. Part of the DevTools Surf developer suite. Browse more tools in the CSS collection.

Use Cases

• Frontend devs migrating vanilla CSS projects to LESS for variable support
• Teams adopting LESS for a Bootstrap 3 based project
• Developers adding nesting to flat CSS files for better organization
• Legacy project maintainers introducing preprocessor features incrementally

Tips

• Review converted variables to ensure correct LESS @variable syntax
• Check that nested selectors follow LESS nesting conventions
• Verify that mixin usage was generated for repeated patterns

Fun Facts

• LESS was created by Alexis Sellier in 2009, originally written in Ruby before being rewritten in JavaScript.
• LESS introduced CSS variables years before native CSS custom properties were specified, using the @ prefix syntax.
• Bootstrap 3 used LESS as its preprocessor before switching to SASS in Bootstrap 4, released in 2018.

FAQ

Does CSS-to-LESS add features automatically?

No — it produces LESS that's syntactically valid but doesn't magically introduce variables or mixins. You still need to refactor common values into @-variables yourself.

What changes between CSS and LESS?

LESS allows nesting, variables (@name), mixins (.name()), and arithmetic. The conversion is mostly a passthrough; the value is that the output is a valid .less starter file.

Will it keep my @media queries?

Yes — and in LESS you can nest media queries inside selectors, which is better style. The tool leaves them at the top level; move them manually for nested style.

Should I use LESS or SCSS today?

SCSS has more momentum and better tooling. LESS is still fine for legacy codebases. If starting fresh, most teams pick SCSS or plain CSS with nesting.