问如何为不同的屏幕调整绝对定位图像的大小？

EN

.banner-sticky {
bottom: -2.5px;
left: 0px;
width: 100%;
text-align: center;
background: rgb(0, 0, 0) transparent;
background: rgba(0, 0, 0, 0);
/* filter:progid:DXImageTransform.Microsoft.gradient(startColorstr=#99000000, endColorstr=#99000000);
-ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr=#99000000, endColorstr=#99000000)";*/
}

.advert-img {
width: 50%
height: auto;
}
@media screen and (max-width: 380px) and (orientation: portrait) {
.advert-img {
width: 100%;
}
}

<meta name="viewport" content="width=device-width, initial-scale=1.0">
.
.
.
<div id="sticky" class="banner-sticky" style="position: fixed;">
  <a id="ad-link" href=' #' ><span id="banner-ad"><img src=' foo.jpg' class="advert-img" /></a>
</div>


'<a id="ad-link" href=' + this.landingUrl + ' ><span id="banner-ad"><img src=' + this.imgSrc + ' class="advert-img" /></a>'