how to put object middle of screen css flex code example

Example 1: css flex vertical align

/* Answer to: "css flex vertical align" */

.box {
  display: flex;
  align-items: center; /* Vertical */
  justify-content: center; /* Horizontal */
}

.box div {
  width: 100px;
  height: 100px;
}

/*
  For more information go to:
  https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flexible_Box_Layout/Aligning_Items_in_a_Flex_Container
*/

Example 2: flex align top css

align-items: flex-start | flex-end | center | baseline | stretch

.container {
  display: flex;
  align-items: flex-start;
}