diff --git a/calendar/templates/event_summary_body.mustache b/calendar/templates/event_summary_body.mustache
index f176f9e7fdf..5aa9f7230c2 100644
--- a/calendar/templates/event_summary_body.mustache
+++ b/calendar/templates/event_summary_body.mustache
@@ -29,6 +29,7 @@
     }
 }}
 <div{{!
+    }} class="summary-modal-container"{{!
     }} data-region="summary-modal-container"{{!
     }} data-event-id="{{id}}"{{!
     }} data-event-title="{{name}}"{{!
@@ -49,7 +50,7 @@
         {{#description}}
         <div class="row m-t-1">
             <div class="col-xs-1">{{#pix}} i/calendareventdescription, core, {{#str}} description {{/str}} {{/pix}}</div>
-            <div class="col-xs-11">{{{.}}}</div>
+            <div class="description-content col-xs-11">{{{.}}}</div>
         </div>
         {{/description}}
         {{#isactionevent}}
diff --git a/theme/boost/scss/moodle/calendar.scss b/theme/boost/scss/moodle/calendar.scss
index 3e3cb04e054..74c9ba32c45 100644
--- a/theme/boost/scss/moodle/calendar.scss
+++ b/theme/boost/scss/moodle/calendar.scss
@@ -417,3 +417,11 @@ table.calendartable caption {
         display: block;
     }
 }
+
+.summary-modal-container {
+    .description-content {
+        > p {
+            margin: 0;
+        }
+    }
+}
diff --git a/theme/bootstrapbase/less/moodle/calendar.less b/theme/bootstrapbase/less/moodle/calendar.less
index 387623de9ec..a201eccc6aa 100644
--- a/theme/bootstrapbase/less/moodle/calendar.less
+++ b/theme/bootstrapbase/less/moodle/calendar.less
@@ -409,3 +409,11 @@
 .calendarwrapper {
     position: relative;
 }
+
+.summary-modal-container {
+    .description-content {
+        > p {
+            margin: 0;
+        }
+    }
+}
diff --git a/theme/bootstrapbase/style/moodle.css b/theme/bootstrapbase/style/moodle.css
index 433f706f667..f08b7c68804 100644
--- a/theme/bootstrapbase/style/moodle.css
+++ b/theme/bootstrapbase/style/moodle.css
@@ -5908,6 +5908,9 @@ img.iconsmall {
 .calendarwrapper {
   position: relative;
 }
+.summary-modal-container .description-content > p {
+  margin: 0;
+}
 /* course.less */
 /* COURSE CONTENT */
 /* stylelint-disable unit-blacklist */
diff --git a/theme/bootstrapbase/templates/core_calendar/event_summary_body.mustache b/theme/bootstrapbase/templates/core_calendar/event_summary_body.mustache
index bcb3c567f74..589c3bba555 100644
--- a/theme/bootstrapbase/templates/core_calendar/event_summary_body.mustache
+++ b/theme/bootstrapbase/templates/core_calendar/event_summary_body.mustache
@@ -29,6 +29,7 @@
     }
 }}
 <div{{!
+    }} class="summary-modal-container"{{!
     }} data-region="summary-modal-container"{{!
     }} data-event-id="{{id}}"{{!
     }} data-event-title="{{name}}"{{!
@@ -49,7 +50,7 @@
         {{#description}}
         <div class="row-fluid m-t-1">
             <div class="span1">{{#pix}} i/calendareventdescription, core, {{#str}} description {{/str}} {{/pix}}</div>
-            <div class="span11">{{{.}}}</div>
+            <div class="description-content span11">{{{.}}}</div>
         </div>
         {{/description}}
         {{#iscategoryevent}}