Index: lams_central/web/css/bootstrap/_modal.scss
===================================================================
diff -u -rb7c92dbcfdb0469dbc0144190a201757f398e529 -ra90d0744dd0d09d1b04869e61ce1b66bf1ee3242
--- lams_central/web/css/bootstrap/_modal.scss	(.../_modal.scss)	(revision b7c92dbcfdb0469dbc0144190a201757f398e529)
+++ lams_central/web/css/bootstrap/_modal.scss	(.../_modal.scss)	(revision a90d0744dd0d09d1b04869e61ce1b66bf1ee3242)
@@ -133,7 +133,7 @@
 
   .btn-close {
     padding: calc(var(--#{$prefix}modal-header-padding-y) * .5) calc(var(--#{$prefix}modal-header-padding-x) * .5);
-    margin: calc(var(--#{$prefix}modal-header-padding-y) * -.5) calc(var(--#{$prefix}modal-header-padding-x) * -.5) calc(var(--#{$prefix}modal-header-padding-y) * -.5) auto;
+    margin: calc(-.5 * var(--#{$prefix}modal-header-padding-y)) calc(-.5 * var(--#{$prefix}modal-header-padding-x)) calc(-.5 * var(--#{$prefix}modal-header-padding-y)) auto;
   }
 }