style(theme): refine font-family (#1162)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

src/client/theme-default/styles/vars.css

@@ -145,10 +145,12 @@
  * -------------------------------------------------------------------------- */
 
 :root {
-  --vp-font-family-base: 'Inter var experimental', 'Inter var', -apple-system,
-    BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell,
-    'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
-  --vp-font-family-mono: Menlo, Monaco, Consolas, 'Courier New', monospace;
+  --vp-font-family-base: 'Inter var experimental', 'Inter var', ui-sans-serif,
+    system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
+    'Helvetica Neue', Helvetica, Arial, 'Noto Sans', sans-serif,
+    'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Noto Color Emoji';
+  --vp-font-family-mono: ui-monospace, SFMono-Regular, 'SF Mono', Menlo, Monaco,
+    Consolas, 'Liberation Mono', 'Courier New', monospace;
 }
 
 /**