html span从上往下，从左往右排序

<html> 
<head> 
<meta charset="utf-8"/> 
<title>从上往下，从左往右</title> 
<style> 
    ＃flex-container {flex-flow：column wrap; } 

    #flex-container > :nth-child(4n - 2) { order: 1; }
    #flex-container > :nth-child(4n - 1) { order: 2; }
    #flex-container > :nth-child(4n - 0) { order: 3; }
    #flex-container > :nth-child(-n + 4) {
        page-break-before: always; /* Old syntax */
        break-before: always;  /* New syntax */
        border-top: 1px solid;
    }
</style> 
</head> 
<body> 

<div id="flex-container">
  <span>1</span>
  <span>2</span>
  <span>3</span>
  <span>4</span>
  <span>5</span>
  <span>6</span>
  <span>7</span>
  <span>8</span>
  <span>9</span>
  <span>10</span>
</div>

</body> 
</html>

2022-12-23
2021-05-16
2021-10-07
2021-10-22
2021-10-16
2022-12-23
2021-08-20