From looking through the code it's easy to see that this theme was originally developed for wordpress using Visual Composer and then screen-scraped using HTTrack website copier.
As such there is loads of messy code all over the place from visual composer - which controls the layout of the body content.
Content blocks are in a nested DIV hell, sometimes up to 10 DIVs deep. This might be fine when managed in wordpress, as was originally intended. But when you are coding by hand this is horrendous to work with.
The author even left in the comments showing that it was screen-scraped:
Loads of wordpress specific classes have been left in, for example in one body class:
page page-id-483 page-template-default melodyschool_body body_style_wide body_filled article_style_stretch layout_single-standard template_single-standard scheme_original top_panel_show top_panel_above sidebar_hide sidebar_outer_hide vc_responsive
To give just one example of a page class.
All in all this makes it very hard to work with as there is so much stuff in the theme that is just not required.
Visually it looks really nice but under the surface it's a right dogs dinner.