In CSS, you can use the ::-webkit-scrollbar pseudo-element to style the scrollbars in webkit-based browsers (e.g., Chrome, Safari).

Here’s an example of how you might use the ::-webkit-scrollbar pseudo-element to change the appearance of the scrollbars:

::-webkit-scrollbar {
    width: 12px;
    background-color: #f5f5f5;
}

::-webkit-scrollbar-thumb {
    background-color: #000000;
    border-radius: 10px;
}

This would change the width of the scrollbar to 12 pixels, set the background color of the scrollbar to #f5f5f5, and set the background color of the scrollbar thumb (the part that you can drag to scroll) to #000000 and give it a 10 pixel border radius.

You can also use the ::-webkit-scrollbar-track pseudo-element to style the track (the area behind the scrollbar thumb).

Here’s an example of how you might use the ::-webkit-scrollbar-track pseudo-element:

::-webkit-scrollbar-track {
    background-color: #eaeaea;
    border-radius: 10px;
}

This would set the background color of the scrollbar track to #eaeaea and give it a 10 pixel border radius.

Note that the ::-webkit-scrollbar pseudo-element is only supported in webkit-based browsers, and it is not supported in other browsers. If you want to style the scrollbars in all browsers, you will need to use a JavaScript library or a CSS polyfill.