如何在css中分三部分创建对角线边框

<div class="container"></div>

.container {
  position: relative;
  width: 200px;
  height: 200px;
}

.container::before,
.container::after {
  content: "";
  position: absolute;
  width: 100%;
  height: 2px;
  background-color: black;
}

.container::before {
  top: 0;
  transform: rotate(45deg);
}

.container::after {
  bottom: 0;
  transform: rotate(-45deg);
}

.container::before,
.container::after {
  left: 50%;
  transform-origin: left;
}

.container::before {
  transform-origin: right;
}

.container::after {
  transform-origin: left;
}