outline: outline (contour) is drawn in a line around the element, located in a peripheral edge of the frame, projecting elements may function.
You may be provided in order the following properties: outline-width, outline-style, outline-color;
outline-offset: outline-offset property profile of the offset, and drawn in the frame edge.
Above are derived from w3school.
code：
border-radius: 20px;
outline-offset: -15px; // offset inwardly 15px;
outline: 1px dashed white;
effect:
