Use jQuery. No way to do it plain html/css.
$('#button').click(function() {
$('#login').css('visibility', 'visible');
});
$('#closelogin').click(function() {
$('#login').css('visibility', 'hidden');
});
If you don't have jQuery included, use javascript:
document.getElementById('button').onclick = function() {
document.getElementById('login').style.visibility = 'visible';
}
document.getElementById('closelogin').onclick = function() {
document.getElementById('login').style.visibility = 'hidden';
}