如何让div居中？

.container {    display: flex;    justify-content: center;    align-items: center;    height: 100vh;}

.container {    display: grid;    place-items: center;    height: 100vh;}

.container {    position: relative;    height: 100vh;}.centered-div {    position: absolute;    top: 50%;    left: 50%;    transform: translate(-50%, -50%);}

.centered-div {    width: 50%;    margin: 0 auto;}

<div class="centered-div">centered content</div>

.container {    text-align: center;    line-height: 100vh; /* full viewport height for vertical centering */}.centered-div {    display: inline-block;    vertical-align: middle;    line-height: normal;}