Answers for "flex center the div"

css flex center

display: flex;
align-items: center;
justify-content: center;

center div css flex

section {
  width: 200px;
  border: 1px solid #2d2d2d;
  display: flex;
  justify-content: center;
}

flex align children to side

flex-direction: column;
align-items: flex-start; //left
align-items: center; //center
align-items: flex-end; //right

center div using flex

<div class="container">
  <div class="item"></div>
</div>

div.container {
  background: gray;
  width: 80px;
  height: 80px;
  display: flex;
  justify-content: center;
  align-items: center;
}

div.item {
  background: silver;
  width: 30px;
  height: 30px;
}