body{
  font-family: Arial, Sans-Serif;
  margin: 20px;
}

.aviso{
  width: 320px;
  padding: 12px;
  border: 4px solid blue;
  outline: 3px solid green;
  outline-offset: 10px;
  text-align: center;
  box-sizing: border-box;
}

.aviso strong{
  display: block;
  margin-bottom: 6px;
}

.aviso p {
  margin: 0 ;
  font-size: 12px;
}