diff --git a/assets/flex-kit/flex-kit.css b/assets/flex-kit/flex-kit.css
index 17342c9..7341f53 100644
--- a/assets/flex-kit/flex-kit.css
+++ b/assets/flex-kit/flex-kit.css
@@ -71,6 +71,7 @@
 }
 
 .flex-list {
+    box-sizing: border-box;
     position: relative;
     display: -ms-flexbox;
     display: -webkit-flex;
@@ -108,6 +109,7 @@
 .flex-list-item {
     --gap-row: var(--gap);
     --col-width: calc((100%) / var(--col-count));
+    box-sizing: border-box;
 }
 .flex-list > .flex-list-item {
     width: var( --col-width) !important;