feat(docs): improve image sizing and add global stylesheet

- Add style.css to head config for global styling
- Refactor image height/width constraints with new classes
- Adjust font size and image ratio thresholds
- Add max-width constraints to prevent overflow

docs/.vitepress/config.mjs

@@ -9,7 +9,8 @@ export default defineConfig({
   title: 'Easy-Vibe Tutorial',
   description: 'Easy-Vibe 中文实战课',
   head: [
-    ['link', { rel: 'icon', href: `${base}logo.png`.replace('//', '/') }]
+    ['link', { rel: 'icon', href: `${base}logo.png`.replace('//', '/') }],
+    ['link', { rel: 'stylesheet', href: `${base}style.css`.replace('//', '/') }]
   ],
   themeConfig: {
     logo: `${base}logo.png`.replace('//', '/'),