post previews: fix css for captioned post previews.

Captioned post previews (previews with the pool name, similarity, or
size beneath) need to have `height: auto` set, otherwise they'll default
to `height: 154px` (just enough for the image) and the caption won't be visible.

app/javascript/src/styles/specific/posts.scss

@@ -13,12 +13,14 @@ article.post-preview {
     @include inline-block;
   }
 
-  &.pooled {
-    height: 214px;
+  &.captioned {
+    height: auto;
+    vertical-align: text-top;
   }
 
   .desc {
    font-size: 80%;
+   margin-bottom: 0;
   }
 
   img {
@@ -34,19 +36,6 @@ article.post-preview {
   }
 }
 
-#iqdb-similar {
-  overflow: hidden;
-
-  .post-preview {
-    height: auto;
-    margin-bottom: 0;
-  }
-
-  p {
-    margin-bottom: 0;
-  }
-}
-
 #saved-searches-nav {
   margin-top: 1em;
 }