Responsive videos and images from WordPress

I am using Ionic to build my app, there is a class item-image to get responsive images, at this point it is not working for me, I am receiving a JSON object from WordPress and some of the images are fine, but other looks odd and way bigger than the width of the screen, and the same with the Youtube videos, I already place a padding and everything, but still can not get it working

here is a Plunker where you might see what I talk about, just enter to the first or post so can see an image, and in second post you can see a video.

I just try

img {
  max-width: 100%;
  height: auto;

and nothing

and here the way I am displaying the content

<script id="tab-post-detail.html" type="text/ng-template">
  <ion-view view-title="Noticia">
  <ion-content has-header="true">
    <div class="list">
      <div class="item item-image text-center item-text-wrap padding">
        <h3 class="item-divider">{{:: post.title}}</h3>
        <p ng-bind-html="trustSrc(post.content)"></p>