div#main {
  width: 100%;
}

div#main {
  width: 100%;
  margin-left: auto;
  margin-right: auto
}

body {
text-align: center;
}

div#main {
  width: 100%;
  margin-left: auto;
  margin-right: auto;
  text-align: left;
}




<style>
body, html {height: 100%;}
#outer {height: 100%; overflow: without overflow;} /* or without overflow */
...
</style>