pinafore/routes/_components/Media.html

<div class="status-media" style="grid-template-columns: repeat(auto-fit, minmax({{minMediaWidth}}px, 1fr));">
  {{#each mediaAttachments as media}}
  <div class="status-media-container {{hasNoNativeWidthHeight(media) ? 'no-native-width-height' : ''}}">
    {{#if media.type === 'video'}}
      <video poster="{{media.preview_url}}"
             src="{{media.url}}"
             width="{{getSmallWidth(media)}}"
             height="{{getSmallHeight(media)}}"
             controls
      />
    {{elseif media.type === 'gifv'}}
    <video
           poster="{{media.preview_url}}"
           src="{{media.url}}"
           width="{{getSmallWidth(media)}}"
           height="{{getSmallHeight(media)}}"
           autoplay
           muted
           loop
           playsinline
    />
    {{else}}
      <img src="{{media.preview_url}}"
           alt="{{media.description || ''}}"
           width="{{getSmallWidth(media)}}"
           height="{{getSmallHeight(media)}}"/>
    {{/if}}
  </div>
  {{/each}}
</div>
<style>
  .status-media {
    grid-area: status-media;
    display: grid;
    align-items: center;
    justify-content: center;
    justify-items: center;
    grid-column-gap: 10px;
    grid-row-gap: 10px;
  }

  .status-media-container {
    overflow: hidden;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
  }
  .no-native-width-height img, .no-native-width-height video {
    background-color: var(--mask-bg);
  }
  .status-media {
    max-width: calc(100vw - 40px);
    overflow: hidden;
  }

  .status-media video, .status-media img {
    max-width: calc(100vw - 40px);
    object-fit: cover;
  }
</style>
<script>
  const DEFAULT_MEDIA_WIDTH = 300
  const DEFAULT_MEDIA_HEIGHT = 200

  export default {
    helpers: {
      getSmallWidth: media => media.meta && media.meta.small && typeof media.meta.small.width === 'number' ?  media.meta.small.width : DEFAULT_MEDIA_WIDTH,
      getSmallHeight: media => media.meta && media.meta.small && typeof media.meta.small.height === 'number' ?  media.meta.small.height : DEFAULT_MEDIA_HEIGHT,
      hasNoNativeWidthHeight: media => !(media && media.meta && media.meta.small && typeof media.meta.small.width === 'number' && typeof media.meta.small.height === 'number'),
    },
    computed: {
      minMediaWidth: (mediaAttachments) => Math.min.apply(Math, mediaAttachments.map(media => media.meta && media.meta.small && typeof media.meta.small.width === 'number' ?  media.meta.small.width : DEFAULT_MEDIA_WIDTH))
    }
  }
</script>