DOCTYPE html> flex : css ul { background: lightpink; } li { display: block; width: 100px;height: 100px; margin: 10px; text-align: center; line-height: 100px; background: #fff; } flex .flex-1 { display: flex; } 1 2 3 .flex-2 { display: flex; flex-direction: column; } 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3..