Center problem in Firefox

In IE, you can use text-align: center to center all elements.
When text-align of the body is center
We insert the following HTML code into the body.
<Div style = "background-color: #006699; width: 800px;"> text content </div>
In IE, we can see that these elements are displayed in the center mode through the color difference of the background;
However, in Firefox, div is left by default, and text is centered. That is to say, in Firefox, text-align is actually only text control.
To reach the DIV center, add a margin: auto to the div.
The final result is
<Div style = "background-color: #006699; width: 800px; margin: Auto"> text content </div>

There is another solution
Add <center>
<Center>
<Div style = "background-color: #006699; width: 800px;"> text content </div>
</Center>

It can also solve the center problem.