style: 调整cover样式

src/pages/post/[...slug].astro

@@ -39,7 +39,7 @@ const published_at = formatDatetime(data.published_at, "YYYY.MM.DD");
     <h1>{data.title}</h1>
 
     {data.cover &&
-      <div class="cover-container">
+      <div>
         <img class="cover" src={data.cover} alt={data.title}>
       </div>
     }
@@ -67,22 +67,9 @@ const published_at = formatDatetime(data.published_at, "YYYY.MM.DD");
     flex-shrink: 0;
   }
 
-  .cover-container {
-    padding-bottom: 56.25%;
-    position: relative;
-    width: 100%;
-    margin-bottom: 24px;
-  }
-
   .cover {
-    position: absolute;
-    left: 0;
-    top: 0;
-    right: 0;
-    bottom: 0;
     width: 100%;
-    height: 100%;
-    object-fit: cover;
+    margin-bottom: 20px;
   }
 
   .meta {
@@ -91,6 +78,7 @@ const published_at = formatDatetime(data.published_at, "YYYY.MM.DD");
     display: flex;
     justify-content: space-between;
     align-items: center;
+    margin-bottom: 20px;
   }
 
   .meta-left {
@@ -107,12 +95,12 @@ const published_at = formatDatetime(data.published_at, "YYYY.MM.DD");
     font-size: 28px;
     line-height: 1.4;
     font-weight: 400;
-    margin: 20px 0 20px;
+    margin-bottom: 20px;
   }
 
   .summary {
     font-size: 14px;
-    margin-bottom: 24px;
+    margin-bottom: 20px;
     color: var(--text-meta);
   }