Sass/Less Integration

In the page layouts of your theme, the finished CSS stylesheets are included. CSS preprocessors like Sass, SCSS or Less are often used to create CSS files. For the following examples we use Sass/SCSS. The Less procedure is otherwise identical, apart from the different language syntax.

Implementation within Contao

Using the preprocessors usually requires a local installation. With Contao you can embed .scss or .less files directly in the page layout. The corresponding CSS files are then created automatically.

Even though the direct use in Contao works, it is still recommended to use ready-to-use CSS files or create them locally using CSS preprocessors.

For our simple example, we will create two files under the files folder: theme.scss and _elements.scss in any directory that is publicly accessible. The theme.scss file contains only one variable with a color value and the _elements.scss file (Sass-partial) via the@import statement. In the _elements.scss file we set the color value for the H1 element using the variable $main-color and a separate color value for a paragraph.

// theme.scss

$mainCol: rgb(255, 0, 0) !default;

@import '_elements';
// _elements.scss

h1 { color: $mainCol; }

p { color: rgb(0, 255, 0); }

Of course, the CSS preprocessors offer much more possibilities. But for our example it is sufficient.

You can now include the file theme.scss in your page layout, similar to the usual procedure with .css files. The file _elements.scss does not need to be selected additionally. Your website should display red H1 headlines and blue text paragraphs.

You can now edit the file theme.scss directly using the Contao file manager, set a different color value for the variable $main-color and save the changes. The H1 caption is printed with the changed color value.

Note I - Handling of Partials

Use the Contao file manager to enter a different color value for the paragraph in the file _elements.scss and save the changes. Unfortunately, this change is not immediately applied in the frontend!

To make your change effective in the Sass partial file, you have to edit the file theme.scss (just insert a blank line and save it) or in the “System Maintenance” you have to empty the Scriptcache.

Note II - CSS preprocessor version

The Contao integration of the CSS preprocessors is done using independent, free PHP libraries. In the case of Sass scssphp/scssphp. Which version is currently used can be found in the respective Contao composer.json.

This is an independent implementation with regard to the Sass functions which does not necessarily correspond to the actual Sass version. So if you want to use Sass functionality in your .scss files according to the current Sass documentation, it might not be supported by the Contao integration. In this case, the only thing that helps is to compare them with the information provided by the scssphp/scssphp developer.


If you follow the instructions above, you can easily work with .scss or .less in Contao. This is especially true if you mainly use variables or Sass partials. The advantage is that you can work directly with the Contao file manager.

On the other hand, you may not have access to all the current functions of the CSS preprocessor versions, which makes troubleshooting difficult.


As mentioned in the beginning, it is recommended to use CSS preprocessors locally. You are independent of the preprocessor version you are using. In Contao, you only include your final .css files.