style: 更新卡片封面样式并移除圆角设计

src/app.css

@@ -323,6 +323,15 @@ body.single-col .post-list {
     border-bottom: 2px solid var(--text-color);
     transition: 0.2s cubic-bezier(0.25, 0.46, 0.45, 0.94) border-color;
   }
+  .card.has-cover {
+    padding-top: 0;
+    padding-left: 0;
+    padding-right: 0;
+  }
+  .card.has-cover .content-wrap {
+    padding-left: 20px;
+    padding-right: 20px;
+  }
   .card-link:hover .card {
     border-color: var(--accent-color);
   }
@@ -1212,16 +1221,18 @@ footer section p:first-child {
   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);
+  }
+}
+
 .post-cover img {
   width: 100%;
   height: 100%;
   object-fit: cover;
   display: block;
-  transition: transform 0.5s ease;
-}
-
-.card-link:hover .post-cover img {
-  transform: scale(1.03);
+  border-radius: 0;
 }
 
 .article-content.has-cover .content-wrap {
@@ -1231,10 +1242,10 @@ footer section p:first-child {
 .detail-cover {
   height: 400px;
   border-bottom: none;
-  border-radius: 8px;
+  border-radius: 0;
   margin-bottom: 30px;
 }
 
 .detail-cover img {
-  border-radius: 8px;
+  border-radius: 0;
 }