Optimize css rules

[duannx]

Currently, style for .carousel__dot is nested inside .carousel__dots. It is unnecessary and makes things a bit verbose when someone wants to overwrite the style of the dot. My suggestion is to remove the parent selector from the style: From:

.carousel__dots .carousel__dot {
    ...
}

To:

.carousel__dot {
    ...
}

By the way, the CSS variable for styling the .carousel__dot is nice to have. I can make a pull request for this.