diff --git a/inst/www/shared/ionrangeslider/scss/_base.scss b/inst/www/shared/ionrangeslider/scss/_base.scss
index fec67457..010de825 100644
--- a/inst/www/shared/ionrangeslider/scss/_base.scss
+++ b/inst/www/shared/ionrangeslider/scss/_base.scss
@@ -4,6 +4,12 @@
     @include pos-r();
     -webkit-touch-callout: none;
     @include no-click();
+    /* https://github.com/rstudio/shiny/issues/3443 */
+    /* https://css-tricks.com/inheriting-box-sizing-probably-slightly-better-best-practice/ */
+    box-sizing: border-box;
+    *, *:before, *:after {
+      box-sizing: inherit;
+    }
 
     &-line {
         @include pos-r();
