LearnWeb

.borders {
  position: relative;
  border: 5px solid #f00;
}

.borders:before {
  content: " ";
  position: absolute;
  z-index: -1;
  top: 5px;
  left: 5px;
  right: 5px;
  bottom: 5px;
  border: 5px solid #ffea00;
}

.borders {
  border: 5px solid blue;
  outline: 5px solid red;
}

.borders{
  box-shadow:
    0 0 0 10px hsl(0, 0%, 80%),
    0 0 0 15px hsl(0, 0%, 90%);/*blur must 0 */
}

.borders{
  border: solid 1px #f06d06;
  padding: 5px;
  background-clip: content-box; /* support: IE9+ */
  background-color: #ccc;
}