how to make anything centered horizontally in css code example

Example 1: how to align elements horizontally in css

.row {
  width: 100%;
  display: flex;
  flex-direction: row;
  justify-content: center;
}
.block {
  width: 100px;
}

Example 2: centering horizontally

div.center{display:block;margin:auto;width:50%;}
p.center{text-align:center;}