Forum layout issue

[hirebuysell]

Hello,
Ive got responsive theme from themeforest and installed it on forum.
There is currently an issue , Not sure with forum or theme so I need help,
In browser when try to zoom out the site ( making window small / smaller ) it works fine but when I try to zoom in for forum it mess whole layout of forum ( sidebar ) and even when I try to zoom out back it still remain same and don't get back to normal.
I've contacted theme owner at themeforest , Here is what they said :

"It's a bad job of the Scripts (not flat theme), try to check the Default Style."

And via email:

Subject: Re: [ThemeForest] Flat vBulletin Theme

One of the vBulletin's scripts adds "l-small" class (when the window is small) to the following block:

<div class="canvas-layout-row has-columns l-row l-row__fixed--right">

and does not remove it (l-small class) while increasing wind


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Em adding screenshots as I may not explain issue better.


Normal:



Small window ( Works Fine )



After zoom in ( Increasing window ), it mess like this and when we zoom out ( make window small ) its like this and messed