style: update border-radius and padding values across components

- standardize border-radius from 8px to 6px for consistent styling
- adjust padding values from 1rem to 0.75rem for better visual hierarchy
- remove redundant overflow-y properties for cleaner code

docs/.vitepress/theme/components/appendix/frontend-engineering/CodeSplittingDemo.vue

@@ -214,10 +214,10 @@ const selectFile = (file) => {
 <style scoped>
 .code-splitting-demo {
   border: 1px solid var(--vp-c-divider);
-  border-radius: 8px;
+  border-radius: 6px;
   background-color: var(--vp-c-bg-soft);
-  padding: 1rem;
-  margin: 1rem 0;
+  padding: 0.75rem;
+  margin: 0.5rem 0;
   font-family: var(--vp-font-family-mono);
 }
 
@@ -236,7 +236,7 @@ const selectFile = (file) => {
   display: grid;
   grid-template-columns: 1fr 1fr;
   gap: 1rem;
-  margin: 1rem 0;
+  margin: 0.5rem 0;
 }
 
 @media (max-width: 768px) {
@@ -248,7 +248,7 @@ const selectFile = (file) => {
 .routes-panel,
 .load-panel {
   background: var(--vp-c-bg);
-  border-radius: 8px;
+  border-radius: 6px;
   border: 1px solid var(--vp-c-divider);
   overflow: hidden;
 }
@@ -263,7 +263,7 @@ const selectFile = (file) => {
 
 .routes-list {
   max-height: 280px;
-  overflow-y: auto;
+  
 }
 
 .route-item {
@@ -355,7 +355,7 @@ const selectFile = (file) => {
 }
 
 .load-visualization {
-  padding: 1rem;
+  padding: 0.75rem;
 }
 
 .load-section {