Container

Container(
  padding: EdgeInsets.all(6),
  height: 25,
  width: 25,
  decoration: BoxDecoration(
    shape: BoxShape.circle,
    color: kInfectedColor.withOpacity(.26),
  ),
  child: Container(
    decoration: BoxDecoration(
      shape: BoxShape.circle,
      color: Colors.transparent,
      border: Border.all(
        color: kInfectedColor,
        width: 2,
      ),
    ),
  ),
),