Different ways to center a div demonstrates how we can center a div using different css properties. It discusses use of 'flex box', 'css grid' and a third way which is not very conventional, i.e by using 'position'.

To center a div using Flex.

Centering a div using flex box is really simple. Here is how.

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

.flex-container {
    display: flex;
    justify-content: center; //center item horizontally
    align-items: center; //center item vertically
    height: 100vh;
}
.item {
    height: 100px;
    width: 100px;
    background: black;
}

Note: You need to give the container a height to center the item vertically.

To center a div using Grid.

Centering a div using grid is even simpler. Here is how.

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

.grid-container {
    display: flex;
    place-items: center; // center's item horizontally and vertically
    height: 100vh;
}
.item {
    height: 100px;
    width: 100px;
    background: black;
}

To center a div using Position.

Centering a div using position is not something you will normally do. Here is how to center a div using position: absolute;.

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

.container {
    position: relative;
    height: 100vh;
}
.item {
    position: absolute;
    height: 100px;
    width: 100px;
    background: black;
}

const container = document.querySelector('.container');
const item = document.querySelector('.item');


// clientHeight/clientWidth gives us the height/width of the element in pixels

item.style.top = (container.clientHeight/2) - (item.clientHeight/2) + 'px';

item.style.left = (container.clientWidth/2) - (item.clientWidth/2) + 'px';

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