@michal.h21 Ok, I will try it now. I assume you mean this macro:
\Configure{graphics*}
{svg}
{\Picture[pict]{\csname Gin@base\endcsname.svg
\space style="width:\CalcRem{\Gin@req@width}em;"
}%
\special{t4ht+@File: \csname Gin@base\endcsname.svg}
}
Your code is too advanced for me, I just copy it and paste it, I really do not know what it does. Will try it. I hope it works, I want to avoid using .xbb files.