Problem with subcategories

I’ve got some subcategories in categories.
http://webfile.ru/e5a70ae41219a264aef91afb0b233d2e
http://webfile.ru/d3f48b5db55dbb88c53d9c07ca6c8602

But after i add a post to any subcategory this subcategory starts look like category
http://webfile.ru/f9d08089c15d90d374ec5cce050e4154
http://webfile.ru/62348469fdd25dc40311180ac94e34f9

And it’s shown in my sidebar, but i don’t want it and i chose not to show hierarchy in category widget in order not to see any subcategories, i need only categories.
http://webfile.ru/a3357926d1929e87220e30bc65e69951

But if i choose to show hierarchy in category widget, all is getting fine, subcategory looks like subcategory
http://webfile.ru/cf1cb5e613e0fdf1fc355d9dac785ad3

How can i fix this?

Thanks!

Categories and sub-categories are powered by wordpress not the theme.
http://codex.wordpress.org/Posts_Categories_Screen

Thank you, Christopher, i’ve just never used subcategories before. It seems a little weird for me, that in sidebar subcategories look like categories, but now i know it was made by WordPress that way. So i’ll be looking for how to customize it then..

Thank you! I’ve meant that the subcategories look like categories in sidebar if i don’t choose to show them hierarchy in category widget, but as Christopher wrote, this is WordPress thing, not the theme’s.
I’ve removed the subcategories from sidebar using this
.children{
display:none;
}