vertically align element in div code example

Example 1: center elements vertically in div

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

Example 2: vertical align into div

#parent {position: relative;}

#child {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    width: 50%;
    height: 30%;
    margin: auto;
}