Prevent Fixed-position Background-image: Cover From Resizing In Mobile Browsers Upon Address Bar Hide

March 31, 2024 Post a Comment

Sorry for a lack of example on this one, but I figure it's easy enough to understand. I have a fixed background on my site, which is currently implemented like this: #background {

Solution 1:

Almost 5 years later, there is finally a fix for this, due to changes in how Safari and now Chrome for Android calculate vh units. Check it out! https://developers.google.com/web/updates/2016/12/url-bar-resizing

I implemented it on this website (can't really show this off on any of the code playgrounds due to them always embedding results in iframes): https://www.cochranesupply.com

Just used the following code on a background element:

#background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background-image: url(../images/background.jpg);
    background-size: cover;
    z-index: -1;
}

And that's all there is to it! Just need Chrome for Android 56, or Safari for iOS (not certain which version but this may have been in Safari for a long time now).

Solution 2:

I ended up creating a workaround for mobile. It may not degrade gracefully, but it's working well for the time being.

window.mobilecheck = function() {
  var check = false;
  (function(a){if(/(android|bb\d+|meego).+mobile|android|ipad|playbook|silk|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(a)||/1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(a.substr(0,4)))check = true})(navigator.userAgent||navigator.vendor||window.opera);
  return check;
 }

 if (window.mobilecheck() == true) {
  var newHeight = $(window).height() + 70;
  $("#background").css("height", newHeight);
 }

I found that mobilecheck function on the internet ( http://detectmobilebrowsers.com/ ). If it returns true, I take my fixed background image container and add 70 to its height. Then when you drag the screen up and the web browser's address bar auto-hides (thus increasing the window height), it has enough extra height such that background-size: cover does not have to jarringly resize the background image to fit the screen again.

I could have just put the entire page into a fixed container and prevented mobile address bars from ever hiding, but I don't like sidestepping an otherwise neat feature of mobile browsers, and I know iOS isn't exactly thrilled with fixed containers that have their own scrollbars (there are workarounds of course, but I'd prefer my content to be in a more standard container).

EDIT: However, this workaround introduces this issue: CSS CHALLANGE: Background-Image with 100% height - White Space when Scrolling Mobile

Solution 3:

For mobile safari you must, unintuitively, attach fixed backgrounds to the html element like so.

html {
    background: url(../img/bg.jpg) no-repeat center center fixed;
    background-size: cover;
    height: 100%;
    overflow: hidden;
}

Then set the scrolling to the body.

body {
    height: 100%;
    overflow: scroll;
}

You'll still need the background div for IE 8 since it doesn't support the background-size property, so mobile browsers should hide it. The cleanest way to do this is to exploit IE 8's inability to read a media query

@mediaonly screen { #background { display: none; }}

Solution 4:

For those still looking around for an answer, you can use the new vw and vh attributes with an element that is position: fixed.

This scrolls while the address bar moves/shrinks/etc., then remains fixed on the page.

#bgimg {
  display: block;
  background: no-repeat url(bg.png);
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 120vh;
}

Solution 5:

Its hard to say without an example but you may be missing width:100% that should stop any resizing with the scroll bar.

Another way to implement a fixed background on mobile is to have a background div with position: absolute and overflow: hidden and all your other background implementations, Then have a content div with overflow-y:scroll; and set the height of the content div using jquery or any other method you choose to get the window height with.

Check out this JS Fiddle for an example.

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