Theme Customizer Version 4.5 Device Preview Buttons

Any idea why my pages stopped loading correctly within the wordpress previewer and the ‘Device Preview’ Buttons at the bottom of the ‘Theme Customizer’ pane disappeard. It seems that after I made an edit using the “basic edit” function and returned to the Gutenburg editing function my pages stopped loading correctly and the Device Preview Buttons [new with Version 4.5] on WordPress’ “Theme Customizer” had disappeared. Somehow the theme seems to have lost it’s size identity. The proper page configuration can be “massaged” into proper alignment by opening and closing the Theme Customizer tool; but as each page is loaded the “fixed header” has grown too tall and needs to be massaged back into shape. Any idea what has gone wrong? Is there any way to fix this? Thanks
see image here: https://1drv.ms/u/s!ArQ3HhIAcmiBhlJ5Ivhp60U3DgRt

ps: I am using ‘Medical Consulting’ – Free WordPress Medical Consulting theme released by keon themes [https://keonthemes.com/medical-consulting-free-wordpress-medical-consulting-theme-is-released/]. It worked perfectly in the beginning; but, something went wrong.

The page I need help with: [log in to see the link]