如何给两个div的一半提供背景色？

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

.container {
  display: flex;
  height: 100px;
}

.left, .right {
  flex: 1;
}

.left {
  background: linear-gradient(to right, red 50%, transparent 50%);
}

.right {
  background: linear-gradient(to right, transparent 50%, blue 50%);
}

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

.container {
  position: relative;
  height: 100px;
}

.left, .right {
  position: absolute;
  top: 0;
  height: 100%;
}

.left {
  left: 0;
  width: 50%;
  background-color: red;
}

.right {
  right: 0;
  width: 50%;
  background-color: blue;
}