diff --git a/src/app/components/url-preview/UrlPreview.css.tsx b/src/app/components/url-preview/UrlPreview.css.tsx
index a62d7c9f9..5eac2acee 100644
--- a/src/app/components/url-preview/UrlPreview.css.tsx
+++ b/src/app/components/url-preview/UrlPreview.css.tsx
@@ -246,11 +246,15 @@ export const EmbedMediaPortrait = style([
   DefaultReset,
   {
     position: 'relative',
-    width: toRem(300),
-    maxWidth: '100%',
-    // 9:16 via the padding-top hack (177.78%) — see EmbedMediaLandscape.
+    // [Gitea #228] `min()` on both axes so the 9:16 ratio holds whatever the
+    // parent's width is. A padding-top percentage resolves against the
+    // CONTAINING BLOCK's width, not the element's, so a bare `177.78%` inside a
+    // wide card made the box ~2x too tall (606px card → 1077px instead of 533).
+    // Capped at the pixel height of a 300px-wide 9:16 box, it is exact when the
+    // parent is at least 300px and falls back to the percentage below that.
+    width: `min(${toRem(300)}, 100%)`,
     height: 0,
-    paddingTop: '177.78%',
+    paddingTop: `min(${toRem(533)}, 177.78%)`,
     margin: '0 auto',
     overflow: 'hidden',
     backgroundColor: color.Surface.Container,
diff --git a/src/app/components/url-preview/UrlPreviewCard.tsx b/src/app/components/url-preview/UrlPreviewCard.tsx
index c037efb0e..ee80f58e3 100644
--- a/src/app/components/url-preview/UrlPreviewCard.tsx
+++ b/src/app/components/url-preview/UrlPreviewCard.tsx
@@ -1203,7 +1203,11 @@ function MediaEmbedCard({
   };
 
   return (
-    <Box direction="Column">
+    // [Gitea #228] `width: 100%` — UrlPreview is a flex ROW, so this column
+    // shrink-to-fits its content. The facade's <img> supplied that width, but
+    // the player <iframe> is absolutely positioned and contributes none, so on
+    // play the whole embed collapsed to the iframe's ~200px intrinsic size.
+    <Box direction="Column" style={{ width: '100%', minWidth: 0 }}>
       {playing && rich ? (
         // Rich post embeds (Instagram/Reddit) are variable-height and self-size.
         <iframe
@@ -1380,7 +1384,9 @@ function TikTokEmbedCard({ url, prev }: { url: string; prev: IPreviewUrlResponse
   );
 
   return (
-    <Box direction="Column">
+    // [Gitea #228] See the video embed above: this column must fill the card's
+    // flex row, not shrink to the iframe's intrinsic width.
+    <Box direction="Column" style={{ width: '100%', minWidth: 0 }}>
       <div ref={mediaRef} className={previewCss.EmbedMediaPortrait}>
         {playing && videoId ? (
           <iframe