how to horizantally center stuff in css code example

Example 1: css center image

.center {
  display: block;
  margin-left: auto;
  margin-right: auto;
}

Example 2: css align items vertical center

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

Example 3: div center

#inner {
  display: table;
  margin: 0 auto;
  border: 1px solid black;
}

#outer {
  border: 1px solid red;
  width:100%
}