how to put container in center of page code example

Example 1: how to put container in center of page

#container
{
    width: 400px;
    margin-left: auto;
    margin-right: auto;
}

Example 2: how to assign something in center inside a div

IMG.displayed {
    display: block;
    margin-left: auto;
    margin-right: auto }
...
<IMG class="displayed" src="..." alt="...">

Example 3: how to put container in center of page

div.InSkinAlignCenter {
margin: 0 auto;
}

Example 4: how to assign something in center inside a div

P { text-align: center }
H2 { text-align: center }