CSS Tools
CSS to LESS Converter
Translate stylesheets from plain CSS to LESS — structure, variables and nesting mapped for you.
In short
Convert CSS to LESS online: syntax, variables and nesting mapped automatically — free, instant, and 100% in your browser.
By NaveenKumar T · Updated
Learn: Sass vs SCSS vs LESS vs Stylus: Choosing a CSS Preprocessor
- Variables & nesting mapped
- Media queries preserved
- Exact error positions
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Example
CSS to LESS: input and output
A toast component using modern CSS — custom properties, native & nesting and a media query inside the rule.
/* Toast notification */
:root { --toast-bg: #1f2937; --toast-fg: #f9fafb; }
.toast {
position: fixed;
bottom: 1rem; right: 1rem;
padding: 0.75rem 1rem;
border-radius: 8px;
background: var(--toast-bg);
color: var(--toast-fg);
box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.3);
& .close { margin-left: 1rem; opacity: 0.7; }
&:hover .close { opacity: 1; }
@media (max-width: 480px) { left: 1rem; right: 1rem; }
}:root {
--toast-bg: #1f2937;
--toast-fg: #f9fafb;
}
.toast {
position: fixed;
bottom: 1rem;
right: 1rem;
padding: 0.75rem 1rem;
border-radius: 8px;
background: var(--toast-bg);
color: var(--toast-fg);
box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.3);
& .close {
margin-left: 1rem;
opacity: 0.7;
}
&:hover .close {
opacity: 1;
}
@media (max-width: 480px) {
left: 1rem;
right: 1rem;
}
}
The structure is already LESS: the nested & .close, &:hover .close and @media blocks are kept as nesting, the custom properties stay as --toast-bg rather than becoming @variables, and the /* Toast notification */ comment is gone.
Learn more
From CSS to LESS: what maps
Source: plain CSS — the universal target every browser parses. Target: LESS — @-prefixed variables, nesting and mixins, brace syntax. Valid CSS is already valid LESS, so conversion is a clean re-format — giving you a working .less file to start layering @variables and nesting onto.
The converter works on a parsed rule tree rather than regex find-replace, which is why nesting depth, selector grouping with commas, & parent references, and @media blocks survive conversion intact.
When teams convert CSS to LESS
The usual trigger is joining an existing LESS codebase: new component styles were prototyped in plain CSS (or extracted from DevTools) and need to live in .less files alongside everything else. Converting first and refactoring second beats hand-porting — the file works immediately, and you introduce @variables for the design tokens as you touch each section rather than in one risky rewrite.
Help
Frequently asked questions
Everything you need to know about the CSS to LESS.
01How do I convert CSS to LESS?
Paste your CSS (or load a file) and press Convert — the stylesheet is parsed into a rule tree and re-emitted as LESS. Copy the result or download it with the right extension.
02Why does the LESS output look like my CSS?
Because CSS is a strict subset of LESS — every CSS sheet IS a LESS sheet. The conversion gives you the file in LESS form so you can refactor toward variables and nesting incrementally.
03What happens to comments, custom properties and native nesting on the way to LESS?
Custom properties (--toast-bg) and var() calls pass through unchanged — they are not turned into @variables, because LESS compiles them as-is. Native nesting is where the conversion earns its keep: & .close, &:hover .close and an @media block inside a rule all become LESS nesting one-to-one, and modern color syntax like rgb(0 0 0 / 0.3) is kept. Comments do not survive — the parser strips /* */ blocks before building the rule tree — so re-add license headers afterwards. Prettier's LESS formatter tidies the result.
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