Answers for "how to center html elements"

css vertical center

/*Remove comment to become a better programmer. */
/* No Flexbox */
.parent {
  position: relative;
}
.child {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
}

/* With Flexbox */

.parent {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

css center

// example 1 
div { display: grid; place-items: center; }

// example 3
div{ display:flex; align-items:center; }

// example 3
div { width: 100%; margin: 0 auto; }

how to center a div element

/*ADD MARGIN auto to left and right*/
.box1{
    width:80%;
    margin:0 auto;
}