How to change main the border?

[yavorski]

Hi, how to change the main top border?
I have tried a lot of things including to modify some highlights, but couldn't make it.

Here are some of the settings I have tried:

{
  "folke/trouble.nvim",
  cmd = { "Trouble" },
  keys = {{ "<A-t>", "<cmd>Trouble<cr>", silent = true, desc = "Trouble" }},
  opts = {
    border = "solid",
    window = {
      border = "solid",
      opts = { border = "solid" },
      config = { border = "solid" },
      winopts = { border = "solid" },
    },
    win = {
      border = "solid",
      opts = { border = "solid" },
      config = { border = "solid" },
      winopts = { border = "solid" },
    },
    preview = {
      border = "solid",
      winopts = { border = "solid" },
      win = {
        opts = {
          border = "solid"
        }
      }
    }
  },
}

Thank you!

[yavorski]

It turns out to be WinSeparator highlight.