Question

I want to have a login form centred on the page. An example is here

I know how to centre an element what I can’t work out is how to centre an element always in the centre of the page even if the browser window changes size

Answer 1

Classic problem. Here’s some example CSS:

#your_element{
    position: fixed;
    left: 50%;
    top: 50%;
    width: 600px;
    height: 400px;
    margin-left: -300px;
    margin-top: -200px;
}

Important bit: the negative margins should be half of the respective dimensions.