This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.

Less in general

The parser libs may ship dedicated information based on the language you want to use.


Example TYPOScript:

page.includeCSS.testLess = EXT:dyncss_test/Resources/Public/Stylesheets/Example.less

Example Overrides (dynamic color settings, dynamic image overrides):

plugin.tx_dyncss {
    register = LOAD_REGISTER
    register {
        inputColor1.cObject = TEXT
        inputColor1.cObject {
            value = {$lessColorScheme}
            split {
                token.char = 124
                returnKey = 0
        inputColor2 < .inputColor1
        inputColor2.cObject.split.returnKey = 1
    overrides {
        inputColor1 = TEXT
        inputColor1 {
            data = register:inputColor1
        inputColor2 = TEXT
        inputColor2 {
            data = register:inputColor2
        logo = IMG_RESOURCE
        logo {
            stdWrap.wrap = url("|")
            file = GIFBUILDER
            file {
                XY = [20.w],[20.h]
                20 = IMAGE
                20.file = GIFBUILDER
                20.file {
                    XY = 128,22
           = register:inputColor1
                20.mask = EXT:example/css/colors/less/images/logo_sw.png
    registerReset = RESTORE_REGISTER

Example less file:

    @linkColor: blue;
    @logo: url(someWeirdUrl);

    a {
        color: @linkColor;

    h1 {
        a {
            color: lighten(@linkColor, 20%);
    #logo {

Backend: Include in backend.php

To see how it works, please take a look into dyncss_test.


In production mode, CSS is only re-rendered if the topmost less or sass file, which is directly included by typoscript, is altered.In development mode, also changes in files that are imported inside a less or sass file trigger a new rendering.Development mode is triggered either by TYPO3 application context "Development" or by the preset "Development" in the install tool. Additionally rerendering will happen if you change TS values, which are used in the less files.

Additionally we add a a new clear cache button to just clear the dyncss cache.

dyncss clear cache

Source maps

If the compiling library supports source maps, you can enable that feature by enabling the debug mode of dyncss in the extensionmanager settings.

Normally the source maps are appended to the generated css files, to avoid confusion.


You need to disable css concetanation to get the sourcemaps working.

This can be done with the following TS based on your environment:

themes.configuration.css.concatenate = 0
page.config.concatenateCss = 0