[6.x] Override z-index of DatePicker inside modals (#13802)

Author: duncanmcclean

resources/css/elements/base.css

@@ -150,4 +150,17 @@ code:not(pre *) {
         color: hsl(from var(--theme-color-ui-accent-bg) h s 90);
         background: hsl(from var(--theme-color-ui-accent-bg) h s 10 / 0.5);
     }
+}
+
+/**
+	Override the z-index of Reka's popper content wrapper under certain conditions.
+	We can't use a direct descendant selector because the DatePicker is inside a Portal.
+*/
+body:has(
+	[data-ui-modal-content],
+	.stack,
+	.live-preview,
+	.code-fullscreen
+) [data-reka-popper-content-wrapper] {
+    z-index: var(--z-index-portal)!important;
 }

resources/js/components/ui/Combobox/Combobox.vue

@@ -555,18 +555,6 @@ defineExpose({
 </template>
 
 <style scoped>
-    /* Override the hardcoded z-index of Reka's popper content wrapper under certain conditions. We can't use a direct descendant selector because the combobox is inside a portal, so instead we'll check to see if certain conditions are present. */
-    body:has(
-        /* A modal is present */
-        [data-ui-modal-content],
-        /* Fullscreen Code Editor fieldtype */
-        .code-fullscreen,
-        .stack,
-        .live-preview
-    ) [data-reka-popper-content-wrapper] {
-        z-index: var(--z-index-portal)!important;
-    }
-
     @supports(text-box: ex alphabetic) {
         [data-ui-badge] {
             padding-block: 0.65rem;