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/canvas-intro/AnimationLoopDemo.vue

@@ -429,7 +429,7 @@ onUnmounted(() => {
 .reset-btn {
   padding: 0.625rem 1.25rem;
   border: none;
-  border-radius: 8px;
+  border-radius: 6px;
   font-size: 0.875rem;
   font-weight: 600;
   cursor: pointer;
@@ -477,7 +477,7 @@ onUnmounted(() => {
   width: 100%;
   padding: 0.5rem 0.75rem;
   border: 2px solid var(--vp-c-divider);
-  border-radius: 8px;
+  border-radius: 6px;
   font-size: 0.875rem;
   background: var(--vp-c-bg);
   cursor: pointer;
@@ -553,7 +553,7 @@ onUnmounted(() => {
 
 canvas {
   border: 3px solid var(--vp-c-divider);
-  border-radius: 8px;
+  border-radius: 6px;
   background: #ffffff;
   box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
 }
@@ -589,7 +589,7 @@ canvas {
   margin: 1.5rem 0;
   padding: 1.25rem;
   background: var(--vp-c-bg);
-  border-radius: 8px;
+  border-radius: 6px;
   border: 1px solid var(--vp-c-divider);
 }