in scripts/lib-franklin.js [575:585]
export function decorateTemplateAndTheme() {
const addClasses = (element, classes) => {
classes.split(',').forEach((c) => {
element.classList.add(toClassName(c.trim()));
});
};
const template = getMetadata('template');
if (template) addClasses(document.body, template);
const theme = getMetadata('theme');
if (theme) addClasses(document.body, theme);
}