p{
  padding: 20px;
  margin: 20px 10px;
  background-color: lightBlue;
}
.p1{
    border: 5px solid black;   
}

.p2{
    border: 5px solid black;
    opacity: 0.5;
}

.p3{
    border: 5px solid RGBa(0, 0, 0, 0.5);
}