how to align something vertically in css code example

Example 1: vertical align css

.container{
  display: table;
}

.div-inside-container{
  display: table-cell;
  vertical-align: middle;
}

Example 2: how to center align the html element in css examples

#inner {
  width: 50%;
  margin: 0 auto;
}

# center text
.center {
  text-align: center;
  
border: 3px solid green;
}