for those div and something that have width and height, we can go to that element style and set it to margin: 0 auto;; but for those having no width like span, a those inline element, we go to their parent element and use: text-align: center
go to the container, and set:
.container {
/* fixed position a zero-height full width container */
position: fixed;
top: 0;
left: 0;
right: 0;
height: 0;
/* center all inline content */
text-align: center;
}