Като центриране на дял в css

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

/* For horizontal align: */
parent-element {text-align:center;}
/* For horizontal and vertical align: */
parent-element {position: relative;}
element-to-be-centered {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

/* See https://www.w3schools.com/css/css_align.asp for more info */

// add to the parent element
.parent{
  	height:100vh;
	display:flex;
  	justify-content: center;
  	align-items: center;
}
or you can use 
// add to the parent element
.parent{
  	height:100vh;
	display:gird;
  	place-item:center;
}

/* html */
<h1>Centering with CSS</h1>

<h3>Text-Align Method</h3>
<div class="blue-square-container">
  <div class="blue-square"></div>
</div>

<h3>Margin Auto Method</h3>
<div class="yellow-square"></div>

<h3>Absolute Positioning Method</h3>
<div class="green-square"></div>

/* css */
h1,
h3 {
  text-align: center;
}

.blue-square-container {
  text-align: center;
}

.blue-square {
  background-color: #0074D9;
  width: 100px;
  height: 100px;
  display: inline-block;
}

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

.container {
  ...
  display: flex;
  justify-content: center;
}