Centering table and submit button CSS

Centering table on my screen works with such CSS lines:

margin-left: auto;
margin-right: auto;

However for submit button it doesn't work, do i need to enter it manually l开发者_如何学Goike margin-right:400px? But if other's people screen has bigger resolution then it won't be in center?

Make use of text-align property for align it center

text-align:center;

Wrap the button with

<center> </center>