use mixin in styles/atoms/_code.scss

packages/app/src/styles/atoms/_code.scss

@@ -1,14 +1,12 @@
 @use '~/styles/variables' as var;
 @use '~/styles/bootstrap/init' as bs;
+@use '~/styles/atoms/mixins' as c;
 
 /*
  * style of inline-code
  */
 :not(pre) {
   > code {
-    padding: 2px 4px;
-    font-family: var.$font-family-monospace-not-strictly;
-    border: 1px solid;
-    border-radius: bs.$border-radius;
+    @include c.code-inline;
   }
 }