property will set the content  horizontally center of a div.

vertical-align:middle; property will set the content  vertically center of a div. but to make the content positioned exactly to fit in the center   line-height:400px; set the line height to the half of the height and width.

HTML:

css:

.container{
    width:400px;
    height:400px;
    background-color:green;
   text-align:center;
   vertical-align:middle;
   line-height:400px;
}

CodePen Ref: Code pen source code

           
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