TestFlex

HTML

<!DOCTYPE html>
<html lang="en">
  <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>
    <style>
      * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
      }
      .container {
        flex: 0 1 960px;
        display: flex;
        height: 300px;
        margin: 0 auto;
        background-color: tomato;
      }
      body {
        height: 100vh;
        width: 100%;
        display: flex;
      }
      .primeiro {
        margin-left: 50px;
        text-align: center;
        width: 250px;
        height: 50px;
        background-color: turquoise;
      }
    </style>
  </head>
  <body>
    <section class="container">
      <div class="primeiro">ola</div>
      <div class="primeiro">hy</div>
    </section>
  </body>
</html>