style(topic-cards): 优化卡片样式和过渡效果

- 将过渡属性从特定属性改为 all 以简化动画效果
- 移除复杂的径向渐变背景和遮罩组合效果
- 添加列表容器的基础样式定义
- 为列表容器添加半透明白色背景层

scss/topic-cards.scss

@@ -84,8 +84,7 @@
   border-radius: var(--d-border-radius);
   cursor: pointer;
   transition:
-    box-shadow 0.2s ease,
-    transform 0.2s ease;
+    all 0.2s ease;
 
   &::before {
     content: "";
@@ -93,21 +92,6 @@
     inset: 0;
     border-radius: inherit;
     padding: 1px;
-    background:
-      radial-gradient(
-        120% 90% at 0% 0%,
-        oklch(from var(--accent-color) calc(l * 1.12) calc(c * 0.55) h / 0.5),
-        transparent 55%
-      ),
-      radial-gradient(
-        120% 90% at 100% 100%,
-        oklch(from var(--accent-color) calc(l * 1.05) calc(c * 0.45) h / 0.35),
-        transparent 58%
-      );
-    -webkit-mask:
-      linear-gradient(#000 0 0) content-box,
-      linear-gradient(#000 0 0);
-    -webkit-mask-composite: xor;
     mask-composite: exclude;
     pointer-events: none;
   }
@@ -780,3 +764,20 @@ body.user-messages-page {
   display: inline-flex;
   position: relative;
 }
+
+.container.list-container{
+  position: relative;
+}
+
+.container.list-container::before{
+  position: absolute;
+  content: "";
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  z-index: -1;
+  width: 100%;
+  height: 100%;
+  background-color: #fff9;
+}