The border-color Property

The color of the border can also be specified using a hexadecimal value (HEX):

A solid red border

A solid blue border

A solid grey border

The internal stylesheet embedded in the head of this page

<style>
p.one {
  border-style: solid;
  border-color: #ff0000; /* red */
}

p.two {
  border-style: solid;
  border-color: #0000ff; /* blue */
}

p.three {
  border-style: solid;
  border-color: #bbbbbb; /* grey */
}
</style>