message: work for : implement auto apply theme
diff: @@ -263,6 +263,26 @@ export class StylesManager {
  "modern": ".sv-root-modern "
  };
  + static autoApplyTheme(): void {
  + const includedThemeCss = StylesManager.getIncludedThemeCss();
  + if(includedThemeCss.length === 1) {
  + StylesManager.applyTheme(includedThemeCss[0].name);
  + }
  + }
  +
  + static getIncludedThemeCss(): Array<any> {
  + const themeMapper = (surveyCss.getAvailableThemes() as Array<string>)
  + .filter(themeName => ["defaultV2", "modern", "default"].indexOf(themeName) !== -1)
  + .map(themeName => { return { name: themeName, theme: surveyCss[themeName] }; });
  +
  + const res = [];
  + if (!!document && !!document.body) {
  + const styles = getComputedStyle(document.body);
  + res.push(themeMapper.filter(item => item.theme.variables && styles.getPropertyValue(item.theme.variables.themeMark))[0]);
  + }
  + return res;
  + }
  +
  static findSheet(styleSheetId: string): any {
  if (typeof document === "undefined") return null;
  for (let i = 0; i < document.styleSheets.length; i++) {
  @@ -344,6 +364,7 @@ export class StylesManager {
  this.initializeStyles(this.sheet);
  }
  }
  + StylesManager.autoApplyTheme();
  }
  public initializeStyles(sheet: CSSStyleSheet): any {
  