css - How to align a div vertically on full unknown width? -

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• how center div in page? (height & width)? 2 answers

i mean, if have div, 200px of height , 200px of width, , want align vertically (i can align horizontaly "margin: auto", but, there way align vertically without knowking height of screen?

thanks , sory english, it's not native language

edit: height of screen

here's example, fiddle

div {   position: absolute;   width: 200px;   height: 200px;   top: 50%;   left: 50%;   margin-top: -100px;   margin-left: -100px; }