Html 同时保持纵横比和居中

我有一个位置=固定的容器（主容器）

这个容器里还有其他容器

  <div class="main-container">
   <div class="container0">
    <div class="container">
        <div class="wrapper">
            <iframe name="case-overlay-iframe" class="preview-iframe voice" allowfullscreen="true" src="https://cc-api-cp.adobe.io/api/v2/voice/assets/4ICee/video/embed?api_key=LucaApp1"></iframe>
        </div>
    </div>
  </div>
</div>

有人能帮忙吗

.main-container {
    position: fixed;
    width: 100%;
    height: 100%;
    z-index: 1005;
    top: 0px;
    left: 0px;
    overflow: auto;
}
.container0 {
    position: absolute;
    min-width: 700px;
    min-height: 400px;
    width: 100%;
    height: 100%;
    left: 0px;
    right: 0px;
    top: 0px;
    bottom: 0px;
    z-index: 200;
    background: #262626;
}

.container {
    background: #1c1c1c;
    width: calc(100% - 440px);
    height: 100%;
    display: flex;
    max-width: 1280px;
    max-height: 720px;
}
.wrapper {
    position: relative;
    height: 0;
    padding-bottom: 56.25%;
    width: 100%;
    margin: auto;
}
iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
}