Our HTML theme have some issues while preview

Hello Everyone,

We are facing some issues on out Fitmate - fitness html theme while we preview our theme via themeforest, when we remove the frame it works fine.
When the theme got approved it was working fine without any issues with Frame as well. today after few days I noticed this issue. Please suggest if this is css or js issues.
Item link: https://themeforest.net/item/fitmate-fitness-studio-html-bootstrap-theme-parallax/19995855

Preview Link: http://preview.themeforest.net/item/fitmate-fitness-studio-html-bootstrap-theme-parallax/full_screen_preview/19995855?_ga=2.182334439.1756157460.1497495950-162587814.1487575387