centre single column flexbox code example
Example 1: flexbox align right and left
.primary-nav {
display:-webkit-flex;
display:flex;
list-style-type:none;
padding:0;
justify-content:flex-end;
}
.left {
margin-right:auto;
}
Example 2: flex align children to side
flex-direction: column;
align-items: flex-start; //left
align-items: center; //center
align-items: flex-end; //right