site: Add missing array to addCssFiles
site: Add missing array to addCssFiles

sil-student-projects/web-languageforge,sil-student-projects/web-languageforge,sil-student-projects/web-languageforge,sil-student-projects/web-languageforge,sil-student-projects/web-languageforge,sil-student-projects/web-languageforge,sil-student-projects/web-languageforge,sil-student-projects/web-languageforge