CSS background-size: cover replacement for Mobile Safari

问题

Hi I have several divs on my page which have background images that I want to expand to cover the entire div which in turn can expand to fill the width of the viewport.

Obviously background-size: cover behaves unexpectedly on iOS devices. I've seen some examples of how to fix it, but I can't make them work in my situation. Ideally I'd prefer not to add extra <img> tags to the HTML but if it's the only way then I will.

Here is my code:

.section {
  margin: 0 auto;
  position: relative;
  padding: 0 0 320px 0;
  width: 100%;
}

#section1 {
  background: url(...) 50% 0 no-repeat fixed;
  background-size: cover;
}

#section2 {
  background: url(...) 50% 0 no-repeat fixed;
  background-size: cover;
}

#section3 {
  background: url(...) 50% 0 no-repeat fixed;
  background-size: cover;
}

<body>
  <div id="section1" class="section">
    ...
  </div>
  <div id="section2" class="section">
    ...
  </div>
  <div id="section3" class="section">
    ...
  </div>
</body>

The question is, how can I get the background image to completely cover the section div, taking into account the variable width of the browser and the variable height of the content in the div?

回答1:

I've had this issue on a lot of mobile views I've recently built.

My solution is still a pure CSS Fallback

http://css-tricks.com/perfect-full-page-background-image/ as three great methods, the latter two are fall backs for when CSS3's cover doesn't work.

HTML

<img src="images/bg.jpg" id="bg" alt="">

CSS

#bg {
  position: fixed; 
  top: 0; 
  left: 0; 

  /* Preserve aspect ratio */
  min-width: 100%;
  min-height: 100%;
}

回答2:

I have had a similar issue recently and realised that it's not due to background-size:cover but background-attachment:fixed.

I solved the issue by using a media query for iPhone and setting background-attachment property to scroll.

For my case:

.cover {
    background-size: cover;
    background-attachment: fixed;
    background-position: center center;

    @media (max-width: @iphone-screen) {
        background-attachment: scroll;
    }
}

Edit: The code block is in LESS and assumes a pre-defined variable for @iphone-screen. Thanks for the notice @stephband.

回答3:

Also posted here: "background-size: cover" does not cover mobile screen

This works on Android 4.1.2 and iOS 6.1.3 (iPhone 4) and switches for desktop. Written for responsive sites.

Just in case, in your HTML head, something like this:

<meta name="viewport" content="width=device-width, initial-scale=1.0"/>

HTML:

<div class="html-mobile-background"></div>

CSS:

html {
    /* Whatever you want */
}
.html-mobile-background {
    position: fixed;
    z-index: -1;
    top: 0;
    left: 0;
    width: 100%;
    height: 125%; /* To compensate for mobile browser address bar space */
    background: url(/images/bg.jpg) no-repeat; 
    background-size: 100% 100%;
}

@media (min-width: 600px) {
    html {
        background: url(/images/bg.jpg) no-repeat center center fixed; 
        background-size: cover;
    }
    .html-mobile-background {
        display: none;
    }
}

回答4:

There are answers over the net that try to solve this, however none of them functioned correctly for me. Goal: put a background image on the body and have background-size: cover; work mobile, without media queries, overflows, or hacky z-index: -1; position: absolute; overlays.

Here is what I did to solve this. It works on Chrome on Android even when keyboard drawer is active. If someone wants to test iPhone that would be cool:

body {
    background: #FFFFFF url('../image/something.jpg') no-repeat fixed top center;
    background-size: cover;
    -webkit-background-size: cover; /* safari may need this */
}

Here is the magic. Treat html like a wrapper with a ratio enforced height relative to the actual viewport. You know the classic responsive tag <meta name="viewport" content="width=device-width, initial-scale=1">? This is why the vh is used. Also, on the surface it would seem like body should get these rules, and it may look ok...until a change of height like when the keyboard opens up.

html {
    height: 100vh; /* set viewport constraint */
    min-height: 100%; /* enforce height */
}

回答5:

For Safari versions <5.1 the css3 property background-size doesn't work. In such cases you need webkit.

So you need to use -webkit-background-size attribute to specify the background-size.

Hence use -webkit-background-size:cover.

Reference-Safari versions using webkit

回答6:

I found the following on Stephen Gilbert's website - http://stephen.io/mediaqueries/. It includes additional devices and their orientations. Works for me!

Note: If you copy the code from his site, you'll want to edit it for extra spaces, depending on the editor you're using.

/*iPad in portrait & landscape*/
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) { /* STYLES GO HERE */}

/*iPad in landscape*/
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) { /* STYLES GO HERE */}

/*iPad in portrait*/
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) { /* STYLES GO HERE */ }

回答7:

That its the correct code of background size :

<div class="html-mobile-background">
</div>

<style type="text/css">
html {
    /* Whatever you want */
}
.html-mobile-background {
    position: fixed;
    z-index: -1;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%; /* To compensate for mobile browser address bar space */
    background: url(YOUR BACKGROUND URL HERE) no-repeat; 
 center center fixed; 
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
 background-size: 100% 100%
}
</style>

回答8:

@media (max-width: @iphone-screen) {
  background-attachment:inherit;    
  background-size:cover;
  -webkit-background-size:cover;
}

回答9:

I found a working solution, the following CSS code example is targeting the iPad:

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) {

    html {  
        height: 100%;
        overflow: hidden;
        background: url('http://url.com/image.jpg') no-repeat top center fixed;
        background-size: cover; 
    }

    body {  
        height:100%;
        overflow: scroll;
        -webkit-overflow-scrolling: touch;
    }

}

Reference link: https://www.jotform.com/answers/565598-Page-background-image-scales-massively-when-form-viewed-on-iPad

回答10:

html body {
  background: url(/assets/images/header-bg.jpg) no-repeat top center fixed;
  width: 100%;
  height: 100%;
  min-width: 100%;
  min-height: 100%;

  -webkit-background-size: auto auto;
  -moz-background-size: auto auto;
  -o-background-size: auto auto;
  background-size: auto auto;
}

来源：https://stackoverflow.com/questions/18429620/css-background-size-cover-replacement-for-mobile-safari

标签

html

css

mobile-safari