add expand icon

src/client/theme-default/styles/components/vp-doc.css

@@ -457,6 +457,7 @@
 
 .vp-doc [class*='language-'] > button.modal {
   top: 64px;
+  background-image: var(--vp-icon-expand);
 }
 
 .vp-doc

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

@@ -87,6 +87,8 @@
   --vp-icon-copy: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' stroke='rgba(128,128,128,1)' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' viewBox='0 0 24 24'%3E%3Crect width='8' height='4' x='8' y='2' rx='1' ry='1'/%3E%3Cpath d='M16 4h2a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V6a2 2 0 0 1 2-2h2'/%3E%3C/svg%3E");
   /* clipboard-copy */
   --vp-icon-copied: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' stroke='rgba(128,128,128,1)' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' viewBox='0 0 24 24'%3E%3Crect width='8' height='4' x='8' y='2' rx='1' ry='1'/%3E%3Cpath d='M16 4h2a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V6a2 2 0 0 1 2-2h2'/%3E%3Cpath d='m9 14 2 2 4-4'/%3E%3C/svg%3E");
+
+  --vp-icon-expand: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' stroke='rgba(128,128,128,1)' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' viewBox='0 0 24 24'%3E%3Cpath d='m21 21-6-6m6 6v-4.8m0 4.8h-4.8'/%3E%3Cpath d='M3 16.2V21m0 0h4.8M3 21l6-6'/%3E%3Cpath d='M21 7.8V3m0 0h-4.8M21 3l-6 6'/%3E%3Cpath d='M3 7.8V3m0 0h4.8M3 3l6 6'/%3E%3C/svg%3E");
 }
 
 /* social icons - used under CC0 1.0 from https://simpleicons.org/ */