CSS two layers respond to a bounce

<!--there will be a picture of the content Background:url (images/123.jpg); Loading background background-size 100% 400px; The width itself can be defined by the height of the second level div height as the limit background-repeat:no-repeat; display only one picture background-position:center; picture is centered--
<div style= "Background:url (images/123.jpg); background-size:100% 400px;background-repeat:no-repeat; Background-position:center; " >
<!--the width of the parent class as the standard outer picture size--
<div style= "Width:90%;height:500px;text-align:center;" >
<!----
<!--percent Second level picture adaptive--
<div style= "Background-position:center;background-image:url (images/1111.jpg); background-size:20% 300px; Background-repeat:no-repeat; ">
<!--set the internal picture size--
<div style= "width:500px; height:500px "></div>
</div>
</div>
</div>

Effect

CSS two layers respond to a bounce