Blog Posts Archive: border and shadow for the boxes

Dear GP-Team,

probably ist for you a very simple question. I want to have borders in the boxes of the blog posts. I could obtain the shadows with this code but I can't change the border-color ( there is no color at all ). My code is:
.archive .inside-article,
.blog .inside-article {

padding: 50px;
border-color: black;
border-radius: 25px;
border: 15px #8e8f92;
box-shadow: 2px 2px #c9c9c9;
}

box-shadow works but no border-color. I tried with border: black; too but it didn't work.

Thank you very much.

Rafael