Bootstrap table without stripe / borders

I’m kinda stuck with a CSS problem while using Bootstrap. I’m also using Angular JS with Angular UI.bootstrap (which might be part of the problem).

I’m making a website that displays data in a table.
Sometime, the data contains object that I have to display in tables.
So I want to put borderless tables inside a normal table while keeping inside separation lines for the borderless tables.

But it seems that even if I specifically say to not show the borders on a table, it is forced:

HTML:

<table class="table borderless">

CSS:

.borderless table {
    border-top-style: none;
    border-left-style: none;
    border-right-style: none;
    border-bottom-style: none;
}

So here, what I want is just the inside borders.