CSS

css horizontal center

#inner {  
	margin: auto 0;
}

#outer {
  width:100%;
  display: flex;
  justify-content: center;
}


<div id="outer">
  <div id="inner">Foo foo</div>
</div>

how to horizontally center in css

.<your-outer-div> {
  display: flex;
  justify-content: center;
  ('align-items: center' will allow you to vertically center too ;))
}

horizontal centering (css)

.container {
  width: 980px;
  margin: 0 auto;
}