> For the complete documentation index, see [llms.txt](https://devworkshops.gitbook.io/masteringvuejs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://devworkshops.gitbook.io/masteringvuejs/styling-the-ui/themes.md).
# Themes
## Working with Sass
Vue CLI projects come with support for pre-processors including Sass, Less, and Stylus. Since a CSS pre-processor was not selected when creating this project, you will need to manually install the corresponding webpack loaders:
```
npm install sass-loader node-sass --save-dev
```
No further configuration is required, as the internal webpack config is pre-configured to handle all pre-processors.
You can now import Sass file types, or use Sass in .vue components as follows:
```markup
```
Now that Sass is enabled, we can swtich from importing **bootstrap.css** to **bootstrap.scss**. First, remove the following imports from **main.js**:
{% code title="main.js" %}
```javascript
...
import 'bootstrap/scss/bootstrap.css'
import 'bootstrap-vue/dist/bootstrap-vue.css'
...
```
{% endcode %}
Then, add a new style block to **App.vue** as follows:
{% code title="App.vue" %}
```markup
...
...
```
{% endcode %}
Save all changes and ensure the site appears normally. In the following topics, you will choose a new theme and customise the sites appearance.
## Customising the theme
In order to customise the theme of the application, you will create a new **.scss** file that contains the required customisation. Within the **assets** folder, create a new file named **custom.scss**. Then update **App.vue** to import the new file:
{% code title="App.vue" %}
```markup
...
...
```
{% endcode %}
You can now customise the appearance of the site by updating the **custom.scss** file. For example, an update to the primary colour would be added as follows:
{% code title="custom.scss" %}
```css
$primary: #c0ff33;
```
{% endcode %}
A good way to get started is to review Bootstrap's **\_variables.scss** file. It contains just over one-hundred lines of Sass that would allow you to customise the entire appearance of your site.
## Choosing a new theme
There are a number of free themes available at [bootswatch.com](https://bootswatch.com/). In this section you will choose a new theme to apply to your application. Start by installing bootswatch:
```
npm install bootswatch --save
```
Next, import the relevant **.scss** files for your chosen theme. For example, if you have chosen Cosmo, update **App.vue** as follows:
{% code title="App.vue" %}
```markup
...
...
```
{% endcode %}
Save all changes and ensure that the site is now using the chosen theme:
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