CSS Property Border-Color Not Working

You need to add the border style:

#box {
    border: 1px solid red;
}

#box{
    border:3px solid #aacfac;
    }

I hope this helps!

I had an issue where it seemed that border-color was not being respected, confusingly it even showed having the right color in the style inspector in Chrome (possibly a Chrome bug). The key thing for me was that if the shorthand border style is specified, it sets all three aspects of the border style, regardless of if they are included or not so:

border-left: 1px;

Actually overwrites both the border-left-style and border-left-color properties even though they weren't included. This can for example cause an inherited style to be overridden and appear not to work.

By default the border-width is 0 and border-style is none

So you need to set them to border-width:1px and border-style:solid. You can combine all the border properties into one as below:

#box {
    border:1px solid red
}