table border

Hello all,

maybe you can help me? i create table with php, and integrate him to wordpress. but there table borders color is same like theme background color.

i create new atributte in css

table
{
border: 1px;
border-color: red;
}

but in website nothing change. Then i saw in inspect element that my table get style from

user agent stylesheet

table {
border-collapse: separate;
border-spacing: 2px;
border-color: gray;
}

my question is, how i can change border color? there i can find this user agent stylesheet and table atributte?

thanks for information ??