styleWhiteKey = function (key) {
        key.el.style.backgroundColor = settings.whiteKeyColour;
        key.el.style.border = '1px solid ' + settings.borderColour;
        key.el.style.borderRight = 0;
        key.el.style.height = settings.height + 'px';
        key.el.style.width = key.width + 'px';
        key.el.style.borderRadius = '0 0 5px 5px';

        if (key.noteNumber === getTotalWhiteKeys() - 1) {
            key.el.style.border = '1px solid ' + settings.borderColour;
        }
    }
Add styling to individual white key.
@param  {element} el White key DOM element.