Answers for "center a div inside a div css"

align a div in center of another div

#container {
    width: 640px; /*can be in percentage also.*/
    height: auto;
    margin: 0 auto;
    padding: 10px;
    position: relative;
}

center a div

<div id="outer">
  <div id="inner">Foo foo</div>
</div>
//css:, demo with border
<style>
#inner {
  display: table;
  margin: 0 auto;
  border: 1px solid black;
}

#outer {
  border: 1px solid red;
  width:100%
}
</style>