code: public String getUriStyleSheet() {
  
          if (m_uriStyleSheet == null) {
              try {
                  if (OpenCms.getWorkplaceManager().getEditorCssHandlers().size() > 0) {
                      // use the configured handlers to determine the CSS to use
                      Iterator<I_CmsEditorCssHandler> i = OpenCms.getWorkplaceManager().getEditorCssHandlers().iterator();
                      while (i.hasNext()) {
                          I_CmsEditorCssHandler cssHandler = i.next();
                          if (cssHandler.matches(getCms(), getParamTempfile())) {
                              m_uriStyleSheet = cssHandler.getUriStyleSheet(getCms(), getParamTempfile());
                              break;
                          }
                      }
                  } else {
                      // for compatibility reasons, read the template property value from the template file to get the CSS
                      String currentTemplate = getUriTemplate();
                      m_uriStyleSheet = getCms().readPropertyObject(
                          currentTemplate,
                          CmsPropertyDefinition.PROPERTY_TEMPLATE,
                          false).getValue("");
                  }
              } catch (CmsException e) {
                  LOG.warn(Messages.get().getBundle().key(Messages.LOG_READ_TEMPLATE_PROP_STYLESHEET_FAILED_0), e);
              }
          }
          return m_uriStyleSheet;
      }
docs: Returns the OpenCms VFS uri of the style sheet of the current page.<p>
  
  @return the OpenCms VFS uri of the style sheet of the current page