fix: 修复桌面端非停靠状态时侧边栏滚动问题

- 站点详情(leftbar_part2)在非停靠状态时不再有滚动条
- 站点详情只在停靠(sticky)状态时才启用滚动
- TODO栏(leftbar_part3)在非停靠状态时也有滚动条和高度限制
- TODO栏智能限制最大高度为50vh，内容超出时可滚动
- 添加TODO栏滚动条样式，与站点详情保持一致
- 删除重复的card-body样式定义

style.css

@@ -2532,12 +2532,13 @@ html.navbar-absolute #leftbar_part2.sticky {
 }
 
 #leftbar_part2_inner {
-	max-height: calc(100vh - 110px - var(--leftbar-part3-height, 0px));
-	overflow-y: auto;
 	padding: 10px;
 }
 
-#leftbar_part2_inner::-webkit-scrollbar {
+#leftbar_part2.sticky #leftbar_part2_inner {
+	max-height: calc(100vh - 110px - var(--leftbar-part3-height, 0px));
+	overflow-y: auto;
+}
 
 	width: 6px;
 
@@ -12486,6 +12487,10 @@ article .post-content .huhua a:before {
 #leftbar_part3 {
 	margin-top: 10px;
 	transition: top 0.3s ease, transform 0.3s ease;
+	max-height: 50vh;
+	overflow: hidden;
+	display: flex;
+	flex-direction: column;
 }
 
 #leftbar_part3.sticky {
@@ -12493,15 +12498,36 @@ article .post-content .huhua a:before {
 	top: calc(80px + var(--leftbar-part2-height, 300px));
 	width: 240px;
 	max-height: var(--leftbar-part3-max-height, 50vh);
-	overflow: hidden;
-	display: flex;
-	flex-direction: column;
 }
 
-#leftbar_part3.sticky .card-body {
+#leftbar_part3 .card-body {
 	overflow-y: auto;
 	flex: 1;
 	min-height: 0;
+	padding: 12px 16px;
+}
+
+#leftbar_part3 .card-body::-webkit-scrollbar {
+	width: 6px;
+}
+
+#leftbar_part3 .card-body::-webkit-scrollbar-track {
+	background: transparent;
+}
+
+#leftbar_part3 .card-body::-webkit-scrollbar-thumb {
+	border-width: 1px;
+	background-color: rgba(0, 0, 0, 0.2);
+}
+
+html.darkmode #leftbar_part3 .card-body::-webkit-scrollbar-thumb {
+	border-width: 1px;
+	background-color: rgba(255, 255, 255, 0.2);
+}
+
+#leftbar_part3 .card-body::-webkit-scrollbar-button {
+	height: 5px;
+	pointer-events: none;
 }
 
 body.leftbar-can-headroom.headroom---unpinned #leftbar_part3.sticky {
@@ -12522,10 +12548,6 @@ html.navbar-absolute #leftbar_part3.sticky {
 	}
 }
 
-#leftbar_part3 .card-body {
-	padding: 12px 16px;
-}
-
 .todo-title {
 	display: flex;
 	align-items: center;