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/api-intro/ApiPlayground.vue

@@ -345,7 +345,7 @@ function sendRequest() {
   background: var(--vp-c-brand);
   color: white;
   border: none;
-  border-radius: 8px;
+  border-radius: 6px;
   font-weight: 600;
   cursor: pointer;
   margin-top: 8px;
@@ -415,7 +415,7 @@ function sendRequest() {
   padding: 12px;
   margin-bottom: 12px;
   overflow-x: auto;
-  overflow-y: auto;
+  
   max-height: 180px;
 }