我写了响应页面。在桌面，桌面和移动设备中必须是具有不同扩展名的图像。如果我在 html img src =“....”中嵌入图片，则所有内容都显示正常。如果我在 css 内容：url 中嵌入图片，则图片不会在firefox浏览器中显示。我只需要在 css 中嵌入它，因为当你减少屏幕图像时会加载另一个。感谢。
<div id="nav_image">
<div id="images">
<div class="div_images"><a href="#"><img src="" class="images" id="img1"></a></div>
<div class="div_images"><a href="#"><img src="" class="images" id="img2"></a></div>
<div class="div_images"><a href="#"><img src="" class="images" id="img3"></a></div>
<div class="div_images"><a href="#"><img src="" class="images" id="img4"></a></div>
</div>
</div>
#nav_image #img1{
content: url(http://images.apple.com/v/home/cm/images/promos/iphone_6s_large.jpg);
}
#nav_image #img2{
content: url(http://images.apple.com/v/home/cm/images/promos/apps_for_earth_large.jpg);
}
#nav_image #img3{
content: url(http://images.apple.com/v/home/cm/images/promos/macbook_large.jpg);
}
#nav_image #img4{
content: url(http://images.apple.com/v/home/cm/images/promos/accessories_large.jpg);
}