diff --git a/theme/boost/scss/moodle/popover-region.scss b/theme/boost/scss/moodle/popover-region.scss
index 98272f07f2c..83d50ef9011 100644
--- a/theme/boost/scss/moodle/popover-region.scss
+++ b/theme/boost/scss/moodle/popover-region.scss
@@ -87,6 +87,7 @@ $content-header-footer-height: $region-header-height + $region-footer-height;
     right: 0;
     top: 0;
     height: $region-container-height;
+    max-height: 80vh;
     width: $region-container-width;
     border: $standard-border;
     transition: height 0.25s;
diff --git a/theme/boost/style/moodle.css b/theme/boost/style/moodle.css
index 053baf8f0d4..495263f8de9 100644
--- a/theme/boost/style/moodle.css
+++ b/theme/boost/style/moodle.css
@@ -36825,6 +36825,7 @@ body {
   right: 0;
   top: 0;
   height: 500px;
+  max-height: 80vh;
   width: 380px;
   border: 1px solid #ddd;
   transition: height 0.25s;
diff --git a/theme/classic/style/moodle.css b/theme/classic/style/moodle.css
index bac39fef371..ddc96d3c708 100644
--- a/theme/classic/style/moodle.css
+++ b/theme/classic/style/moodle.css
@@ -36759,6 +36759,7 @@ body {
   right: 0;
   top: 0;
   height: 500px;
+  max-height: 80vh;
   width: 380px;
   border: 1px solid #ddd;
   transition: height 0.25s;