Cannot erase border from bootstrap drop down menu

Question

So I use this Bootstrap structure on my own project.

When the window gets smaller, and the drop down menu is collapsed , as you can see in the image, there is a small border there that will not go away (inside black circle).

At first it was white, so I overwrite the css style and change its color to match the background. But this small border of slightly different color will not go away. I try setting border-style: none; for #navbar, nothing. I set

*{
  border-style: none;
}

for the whole page and still this border will not go away.

How do I make it go away? Maybe its part of the animation? Because when the drop down menu is up, it goes away. Please help me

Thanks

Answer 1

Use this css

.navbar-collapse {
    border: 0;
    box-shadow: none;
}