box-shadow property adds a shadow to an element.
It is allowed to use several shadows, specifying their parameters separated by commas; when shadows are applied, the first shadow in the list will be higher, the last one lower. If a rounding radius is set for an element through the
border-radius property, then the shadow will also turn out with rounded corners. Adding a shadow increases the width of the element, so it is possible for a horizontal scrollbar to appear in the browser.
box-shadow: none | shadow;