Theme conflict and plugin doesn't display

Hello, I’d really like to display these collapsing archives on my WP site blog side bar but it unfortunately seems to be conflicting with the theme I am using.

I talked to the theme developer (I’d purchased it on ThemeForest and slightly modified, though I’m not developer), he recommended adding a few lines of custom CSS which I’ve done (copied & pasted) so now the plugin displays on the side bar of the main blog page, but doesn’t display on individual blog post pages.

I use this theme: themeforest.net/item/ibuki-creative-multipurpose-shop-theme/8179978

On this website: http://www.icecreamforeveryone.net

Could anyone help please?

Main blog page: http://www.icecreamforeveryone.net/blog-eng/

Individual post page: http://www.icecreamforeveryone.net/2016/02/05/ep-11-ed-jowett-roleplaying-game-designer-behind-the-scenes-of-era-the-consortium-secret-war-kickstarter-part-2/

Last message from the Theme developer for reference:

The classes used by the plugin create a conflict with the basic classes used from bootstrap.

Only solution is modded the plugin and also the class or contact the developer of the plugin and ask to change this.

Use firebug or web inspector to find the classes

https://ww.wp.xz.cn/plugins/collapsing-archives/