diff --git a/basic/_common.scss b/basic/_common.scss
index b6fb513..4c46c5a 100644
--- a/basic/_common.scss
+++ b/basic/_common.scss
@@ -38,6 +38,16 @@
 	margin-left: 0;
 }
 
+%size_content {
+	box-sizing: content-box;
+	
+	*,
+	::before,
+	::after {
+		box-sizing: inherit;
+	}
+}
+
 
 
 // Structure attributes