diff --git a/theme/boost/scss/moodle/calendar.scss b/theme/boost/scss/moodle/calendar.scss
index 5db0a490d09..7334988bf50 100644
--- a/theme/boost/scss/moodle/calendar.scss
+++ b/theme/boost/scss/moodle/calendar.scss
@@ -1,30 +1,56 @@
 /* calendar.less */
 
 // Calendar colour variables defined.
-$calendarEventCategoryColor: #d8bfd8 !default; // Pale purple.
+$calendarEventCategoryColor: #e0cbe0 !default; // Pale purple.
 $calendarEventCourseColor: #ffd3bd !default; // Pale red.
 $calendarEventGlobalColor: #d6f8cd !default; // Pale green.
 $calendarEventGroupColor: #fee7ae !default; // Pale yellow.
 $calendarEventUserColor: #dce7ec !default; // Pale blue.
 
+// Border colours for the event colour indicators.
+$calendarEventCategoryBorder: 2px solid #9e619f !default; // Purple.
+$calendarEventCourseBorder: 2px solid #d34600 !default; // Red-orange.
+$calendarEventGlobalBorder: 2px solid #2b8713 !default; // Green.
+$calendarEventGroupBorder: 2px solid #9a6e02 !default; // Dark orange.
+$calendarEventUserBorder: 2px solid #4e7c91 !default; // Blue.
+$calendarEventOtherBorder: 2px solid #687889 !default; // Gray.
+
+// This will be the colour of mini-calendar links, hide/show filter icons, edit/delete icon buttons.
+$calendarEventColor: #0d5ca1 !default;
+
 // Calendar event background colours defined.
 .calendar_event_category {
     background-color: $calendarEventCategoryColor;
+    .commands a {
+        color: $calendarEventColor;
+    }
 }
 .calendar_event_course {
     background-color: $calendarEventCourseColor;
+    .commands a {
+        color: $calendarEventColor;
+    }
 }
 
 .calendar_event_site {
     background-color: $calendarEventGlobalColor;
+    .commands a {
+        color: $calendarEventColor;
+    }
 }
 
 .calendar_event_group {
     background-color: $calendarEventGroupColor;
+    .commands a {
+        color: $calendarEventColor;
+    }
 }
 
 .calendar_event_user {
     background-color: $calendarEventUserColor;
+    .commands a {
+        color: $calendarEventColor;
+    }
 }
 
 // Calendar restyling.
@@ -134,21 +160,26 @@ $calendarEventUserColor: #dce7ec !default; // Pale blue.
 
                             &.calendar_event_category {
                                 background-color: $calendarEventCategoryColor;
+                                border: $calendarEventCategoryBorder;
                             }
                             &.calendar_event_course {
                                 background-color: $calendarEventCourseColor;
+                                border: $calendarEventCourseBorder;
                             }
 
                             &.calendar_event_site {
                                 background-color: $calendarEventGlobalColor;
+                                border: $calendarEventGlobalBorder;
                             }
 
                             &.calendar_event_group {
                                 background-color: $calendarEventGroupColor;
+                                border: $calendarEventGroupBorder;
                             }
 
                             &.calendar_event_user {
                                 background-color: $calendarEventUserColor;
+                                border: $calendarEventUserBorder;
                             }
                         }
                     }
@@ -282,6 +313,7 @@ $calendarEventUserColor: #dce7ec !default; // Pale blue.
                 width: 100%;
                 height: 100%;
                 display: block;
+                color: $calendarEventColor;
             }
 
             &.duration_global {
@@ -373,6 +405,36 @@ $calendarEventUserColor: #dce7ec !default; // Pale blue.
             margin-bottom: 0.2em;
 
             span {
+                &.calendar_event_category {
+                    i {
+                        color: $calendarEventColor;
+                    }
+                }
+                &.calendar_event_course {
+                    i {
+                        color: $calendarEventColor;
+                    }
+                }
+                &.calendar_event_site {
+                    i {
+                        color: $calendarEventColor;
+                    }
+                }
+                &.calendar_event_group {
+                    i {
+                        color: $calendarEventColor;
+                    }
+                }
+                &.calendar_event_user {
+                    i {
+                        color: $calendarEventColor;
+                    }
+                }
+                &.calendar_event_other {
+                    i {
+                        color: $calendarEventColor;
+                    }
+                }
                 img {
                     padding: 0 0.2em;
                     margin: 0;
diff --git a/theme/boost/style/moodle.css b/theme/boost/style/moodle.css
index 16c11c4f5a6..61fa4538ae3 100644
--- a/theme/boost/style/moodle.css
+++ b/theme/boost/style/moodle.css
@@ -12361,19 +12361,29 @@ body.h5p-embed .h5pmessages {
 
 /* calendar.less */
 .calendar_event_category {
-  background-color: #d8bfd8; }
+  background-color: #e0cbe0; }
+  .calendar_event_category .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_course {
   background-color: #ffd3bd; }
+  .calendar_event_course .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_site {
   background-color: #d6f8cd; }
+  .calendar_event_site .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_group {
   background-color: #fee7ae; }
+  .calendar_event_group .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_user {
   background-color: #dce7ec; }
+  .calendar_event_user .commands a {
+    color: #0d5ca1; }
 
 .path-calendar .calendartable {
   width: 100%;
@@ -12450,15 +12460,20 @@ body.h5p-embed .h5pmessages {
           border-radius: 6px;
           vertical-align: middle; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_category {
-            background-color: #d8bfd8; }
+            background-color: #e0cbe0;
+            border: 2px solid #9e619f; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_course {
-            background-color: #ffd3bd; }
+            background-color: #ffd3bd;
+            border: 2px solid #d34600; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_site {
-            background-color: #d6f8cd; }
+            background-color: #d6f8cd;
+            border: 2px solid #2b8713; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_group {
-            background-color: #fee7ae; }
+            background-color: #fee7ae;
+            border: 2px solid #9a6e02; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_user {
-            background-color: #dce7ec; }
+            background-color: #dce7ec;
+            border: 2px solid #4e7c91; }
     .path-calendar .maincalendar .calendarmonth td {
       height: 5em; }
     .path-calendar .maincalendar .calendarmonth .clickable:hover {
@@ -12479,7 +12494,7 @@ body.h5p-embed .h5pmessages {
     color: #0b4f8a;
     text-decoration: underline; }
   .path-calendar .maincalendar .calendar_event_category {
-    border-color: #d8bfd8; }
+    border-color: #e0cbe0; }
   .path-calendar .maincalendar .calendar_event_course {
     border-color: #ffd3bd; }
   .path-calendar .maincalendar .calendar_event_site {
@@ -12518,17 +12533,18 @@ body.h5p-embed .h5pmessages {
   .block .minicalendar td a {
     width: 100%;
     height: 100%;
-    display: block; }
+    display: block;
+    color: #0d5ca1; }
   .block .minicalendar td.duration_global {
     border-top: 1px solid #d6f8cd;
     border-bottom: 1px solid #d6f8cd; }
     .block .minicalendar td.duration_global.duration_finish {
       background-color: #d6f8cd; }
   .block .minicalendar td.duration_category {
-    border-top: 1px solid #d8bfd8;
-    border-bottom: 1px solid #d8bfd8; }
+    border-top: 1px solid #e0cbe0;
+    border-bottom: 1px solid #e0cbe0; }
     .block .minicalendar td.duration_category.duration_finish {
-      background-color: #d8bfd8; }
+      background-color: #e0cbe0; }
   .block .minicalendar td.duration_course {
     border-top: 1px solid #ffd3bd;
     border-bottom: 1px solid #ffd3bd; }
@@ -12575,6 +12591,18 @@ body.h5p-embed .h5pmessages {
 
 .block .calendar_filters li {
   margin-bottom: 0.2em; }
+  .block .calendar_filters li span.calendar_event_category i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_course i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_site i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_group i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_user i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_other i {
+    color: #0d5ca1; }
   .block .calendar_filters li span img {
     padding: 0 0.2em;
     margin: 0; }
diff --git a/theme/classic/style/moodle.css b/theme/classic/style/moodle.css
index 147b72ffe78..c2bca599148 100644
--- a/theme/classic/style/moodle.css
+++ b/theme/classic/style/moodle.css
@@ -12601,19 +12601,29 @@ body.h5p-embed .h5pmessages {
 
 /* calendar.less */
 .calendar_event_category {
-  background-color: #d8bfd8; }
+  background-color: #e0cbe0; }
+  .calendar_event_category .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_course {
   background-color: #ffd3bd; }
+  .calendar_event_course .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_site {
   background-color: #d6f8cd; }
+  .calendar_event_site .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_group {
   background-color: #fee7ae; }
+  .calendar_event_group .commands a {
+    color: #0d5ca1; }
 
 .calendar_event_user {
   background-color: #dce7ec; }
+  .calendar_event_user .commands a {
+    color: #0d5ca1; }
 
 .path-calendar .calendartable {
   width: 100%;
@@ -12690,15 +12700,20 @@ body.h5p-embed .h5pmessages {
           border-radius: 6px;
           vertical-align: middle; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_category {
-            background-color: #d8bfd8; }
+            background-color: #e0cbe0;
+            border: 2px solid #9e619f; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_course {
-            background-color: #ffd3bd; }
+            background-color: #ffd3bd;
+            border: 2px solid #d34600; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_site {
-            background-color: #d6f8cd; }
+            background-color: #d6f8cd;
+            border: 2px solid #2b8713; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_group {
-            background-color: #fee7ae; }
+            background-color: #fee7ae;
+            border: 2px solid #9a6e02; }
           .path-calendar .maincalendar .calendarmonth ul li .badge.badge-circle.calendar_event_user {
-            background-color: #dce7ec; }
+            background-color: #dce7ec;
+            border: 2px solid #4e7c91; }
     .path-calendar .maincalendar .calendarmonth td {
       height: 5em; }
     .path-calendar .maincalendar .calendarmonth .clickable:hover {
@@ -12719,7 +12734,7 @@ body.h5p-embed .h5pmessages {
     color: #0b4f8a;
     text-decoration: underline; }
   .path-calendar .maincalendar .calendar_event_category {
-    border-color: #d8bfd8; }
+    border-color: #e0cbe0; }
   .path-calendar .maincalendar .calendar_event_course {
     border-color: #ffd3bd; }
   .path-calendar .maincalendar .calendar_event_site {
@@ -12758,17 +12773,18 @@ body.h5p-embed .h5pmessages {
   .block .minicalendar td a {
     width: 100%;
     height: 100%;
-    display: block; }
+    display: block;
+    color: #0d5ca1; }
   .block .minicalendar td.duration_global {
     border-top: 1px solid #d6f8cd;
     border-bottom: 1px solid #d6f8cd; }
     .block .minicalendar td.duration_global.duration_finish {
       background-color: #d6f8cd; }
   .block .minicalendar td.duration_category {
-    border-top: 1px solid #d8bfd8;
-    border-bottom: 1px solid #d8bfd8; }
+    border-top: 1px solid #e0cbe0;
+    border-bottom: 1px solid #e0cbe0; }
     .block .minicalendar td.duration_category.duration_finish {
-      background-color: #d8bfd8; }
+      background-color: #e0cbe0; }
   .block .minicalendar td.duration_course {
     border-top: 1px solid #ffd3bd;
     border-bottom: 1px solid #ffd3bd; }
@@ -12815,6 +12831,18 @@ body.h5p-embed .h5pmessages {
 
 .block .calendar_filters li {
   margin-bottom: 0.2em; }
+  .block .calendar_filters li span.calendar_event_category i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_course i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_site i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_group i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_user i {
+    color: #0d5ca1; }
+  .block .calendar_filters li span.calendar_event_other i {
+    color: #0d5ca1; }
   .block .calendar_filters li span img {
     padding: 0 0.2em;
     margin: 0; }