fix(frontend): align post thumbnail display with reference

assets/css/frontend/post-card.css

@@ -103,21 +103,6 @@
   margin: 0 !important;
 }
 
-.item-thumbnail .dplayer.dplayer-thumb {
-  position: absolute;
-  inset: 0;
-  z-index: 1;
-  padding-bottom: var(--posts-list-scale, 70%);
-  background: #000;
-  opacity: 0;
-  transition: opacity 0.3s;
-}
-
-.card .item-thumbnail .dplayer.dplayer-thumb {
-  padding-bottom: var(--posts-card-scale, 70%);
-}
-
-.item-thumbnail .dplayer-thumb video,
 .item-thumbnail .swiper-wrapper,
 .item-thumbnail img {
   position: absolute;
@@ -135,14 +120,6 @@
   text-align: center !important;
 }
 
-.posts-item.thumb-dplayer-playing .dplayer-thumb {
-  opacity: 1;
-}
-
-.posts-item.thumb-dplayer-playing .abs-center {
-  opacity: 0;
-}
-
 .posts-item .item-heading {
   display: -webkit-box;
   max-height: 2.8em;