src/Helpers/Request/HtmlHelper.php
public function cssFile($url, $options = [], $encoding = null)
    {
        $arguments = [$url, $options, $encoding];
        $this->injectVariableToArguments($this->app->charset, $arguments, -1);
        $arguments[] = $this->app;
        return $this->proxy(__FUNCTION__, $arguments);
    }
public function cssFile($url, $options = [], $encoding = null)
    {
        $arguments = [$url, $options, $encoding];
        $this->injectVariableToArguments($this->app->charset, $arguments, -1);
        $arguments[] = $this->app;
        return $this->proxy(__FUNCTION__, $arguments);
    }
Generates a link tag that refers to an external CSS file.
@param array|string $url the URL of the external CSS file. This parameter will be processed by [[Url::to()]].
@param array $options the tag options in terms of name-value pairs. The following options are specially handled:

- condition: specifies the conditional comments for IE, e.g., `lt IE 9`. When this is specified,
the generated `link` tag will be enclosed within the conditional comments. This is mainly useful
for supporting old versions of IE browsers.
- noscript: if set to true, `link` tag will be wrapped into `<noscript>` tags.

The rest of the options will be rendered as the attributes of the resulting link tag. The values will
be HTML-encoded using [[encode()]]. If a value is null, the corresponding attribute will not be rendered.
See [[renderTagAttributes()]] for details on how attributes are being rendered.
@param string $encoding
@return string the generated link tag
@see Url::to()
@see Html::cssFile()