Certainly! In CSS (Cascading Style Sheets), the `border-color` property is used to specify the color of the border of an HTML element. You can set the border color using various color representations, such as named colors, hexadecimal values, RGB values, or HSL values.
For example, if you want to set the border color of an element to red, you can use:
```css
element {
border-color: red;
}
```
You can also use other color representations like hexadecimal:
```css
element {
border-color: #FF0000; /* Red color using hexadecimal */
}
```
Or RGB:
```css
element {
border-color: rgb(255, 0, 0); /* Red color using RGB values */
}
```
And HSL:
```css
element {
border-color: hsl(0, 100%, 50%); /* Red color using HSL values */
}
```
Remember to replace "element" with the actual selector of the HTML element you want to style.
