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/cache-design/CacheArchitectureDemo.vue

@@ -121,10 +121,10 @@ const simulateRequest = () => {
 <style scoped>
 .cache-architecture-demo {
   border: 1px solid var(--vp-c-divider);
-  border-radius: 8px;
+  border-radius: 6px;
   background: var(--vp-c-bg-soft);
-  padding: 1rem;
-  margin: 1rem 0;
+  padding: 0.75rem;
+  margin: 0.5rem 0;
 }
 
 .demo-header {
@@ -166,7 +166,7 @@ const simulateRequest = () => {
   flex-direction: column;
   align-items: center;
   gap: 0.5rem;
-  padding: 1rem;
+  padding: 0.75rem;
   border-radius: 12px;
   transition: all 0.3s;
 }
@@ -316,7 +316,7 @@ const simulateRequest = () => {
   background: var(--vp-c-brand);
   color: white;
   border: none;
-  border-radius: 8px;
+  border-radius: 6px;
   font-size: 0.95rem;
   font-weight: 600;
   cursor: pointer;