feat: 暗色主题、主题切换按钮

src/components/Post/List.astro

@@ -28,12 +28,12 @@ const {posts} = Astro.props
     align-items: baseline;
     gap: 20px;
     padding: 26px 0;
-    border-bottom: 1px solid #e8e8e8;
+    border-bottom: var(--border-secondary);
   }
 
   .post .d {
     font-size: 14px;
-    color: #b8b8b8;
+    color: var(--text-secondary);
     min-width: 80px;
     letter-spacing: 1px;
   }
@@ -42,18 +42,18 @@ const {posts} = Astro.props
     font-size: 16px;
     font-weight: normal;
     flex: 1;
+  }
+
+  .post h2 a {
+    color: var(--text-primary);
+    text-decoration: none;
     white-space: nowrap;
     text-overflow: ellipsis;
     overflow: hidden;
   }
 
-  .post h2 a {
-    color: #181818;
-    text-decoration: none;
-  }
-
   .post h2 a:hover {
-    color: #334155;
+    color: var(--text-title-hover);
     text-decoration: underline;
     text-underline-offset: 6px;
   }