flex容器的项目属性 -

<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div class="container">
    <div class="item">item1</div>
    <div class="item">item2</div>
    <div class="item">item3</div>
  </div>
  <style>
    .container {
      display: flex;
      width: 450px;
      height: 50px;
      /* flex-direction: row;
      flex-wrap: nowrap;
      flex-flow: row wrap;
      place-content: start;
      place-content: end;
      place-content: center;
      place-items: stretch;
      place-items: start;
      place-items: end;
      place-content: space-between;
      place-content: space-around;
      place-content: space-evenly; */
    }
    .container > .item {
      background-color: aqua;
      /* height: 50px; */
      width: 170px;
      flex: 0 1 auto;
      flex: initial;
      flex: 1 1 auto;
      flex: auto;
      flex: 0 0 auto;
      flex: none;
    }
    .container .item:first-child,.container .item:last-child {
      background-color: darkgoldenrod;
      place-self: start;
    }
  </style>
</body>
</html>