added border-color in kibela

src/client/styles/scss/theme/kibela.scss

@@ -51,6 +51,7 @@ html[dark] {
   // border colors
   $border-color-theme: $lightthemecolor;
   $thickborder: #5584e1;
+  $bordercolor-inline-code: $lightthemecolor;
 
   // dropdown colors
   $bgcolor-dropdown-link-active: $growi-blue;