style: modify markdown font-family.

Author: jaywcjlove

src/styles/markdown.less

@@ -194,8 +194,7 @@ body[data-color-mode*='light'] {
 
 .wmde-markdown {
   -webkit-text-size-adjust: 100%;
-  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji',
-    'Segoe UI Emoji';
+  font-family: -apple-system, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji';
   font-size: 16px;
   line-height: 1.5;
   word-wrap: break-word;