Position element over background image. But the BG img changes size with the window. CSS -


i have background image changes size windows size, , need position element on in same place relative background image.

how!?

css

background:url("http://placehold.it/100x100") no-repeat center center fixed; -webkit-background-size:"cover"; -moz-background-size:"cover"; -o-background-size:"cover"; background-size:"cover";

the background image covers entire background , changes size window keeps proportions having overlay.

edit - 2016

my solution pure css position element in middle , offset correctly using calc function. , resize accordingly use vmin value:

$offset-top: ...; $offset-left: ...;  .element {   top: 50%;   left: 50%;   transform: translate(calc(-50% + #{$offset-top}), calc(-50% + #{$offset-top}));   width: 50vim;    height: 50vim; }

what asking not trivial thing @ all, involves figuring out how background-size:cover works , positioning element using javascript. due nature of background-size:cover how image can flow out of x-axis or y-axis cannot done css.

here solution problem, on load , resize calculates scale of image , x or y offset , draws pointer @ relevant location.

jsfiddle (red dot in google's red 'o')

enter image description here

html

<div id="pointer"></div>

css

body {     background:url(https://www.google.com.au/images/srpr/logo4w.png) no-repeat center center fixed;     -webkit-background-size:cover;     -moz-background-size:cover;     -o-background-size:cover;     background-size:cover; }  #pointer {     margin-left:-10px;     margin-top:-10px;     width:20px;     height:20px;     background-color:#f00;     position:fixed; }

js

var image = { width: 550, height: 190 }; var target = { x: 184, y: 88 };  var pointer = $('#pointer');  $(document).ready(updatepointer); $(window).resize(updatepointer);  function updatepointer() {     var windowwidth = $(window).width();     var windowheight = $(window).height();      // largest dimension increase     var xscale = windowwidth / image.width;     var yscale = windowheight / image.height;     var scale;     var yoffset = 0;     var xoffset = 0;      if (xscale > yscale) {         // image fits in x axis, stretched in y         scale = xscale;         yoffset = (windowheight - (image.height * scale)) / 2;     } else {         // image fits in y axis, stretched in x         scale = yscale;         xoffset = (windowwidth - (image.width * scale)) / 2;     }      pointer.css('top', (target.y) * scale + yoffset);     pointer.css('left', (target.x) * scale + xoffset); }

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