style: 移除文章封面底部的边框样式

src/app.css

@@ -1218,13 +1218,7 @@ footer section p:first-child {
   width: 100%;
   height: 300px;
   overflow: hidden;
-  border-bottom: 1px dashed var(--line-color, rgba(0,0,0,0.1));
-}
-
-@media screen and (min-width: 767px) {
-  .card .post-cover {
-    border-bottom: 2px solid var(--text-color);
-  }
+  border-bottom: none;
 }
 
 .post-cover img {