diff --git a/assets_shared b/assets_shared
index 52a05c4..0cdfbd5 160000
--- a/assets_shared
+++ b/assets_shared
@@ -1 +1 @@
-Subproject commit 52a05c428631d617fee9f50ced9adfeef19ce3d9
+Subproject commit 0cdfbd54f695493a549f87162a6a43f29b7f053f
diff --git a/conference/settings.py b/conference/settings.py
index 0b45e60..9b06ade 100644
--- a/conference/settings.py
+++ b/conference/settings.py
@@ -269,7 +269,7 @@ PIPELINE = {
             'output_filename': 'js/festival-finals.js',
         },
         'web-assets': {
-            'source_filenames': ('tutti/10_navbar.js',),
+            'source_filenames': ('tutti/10_navbar.js', 'tutti/20_theme.js',),
             'output_filename': 'js/web-assets.js',
             'extra_context': {'async': True, 'defer': True},
         },
diff --git a/conference_main/static/conference_main/styles/_schedule.sass b/conference_main/static/conference_main/styles/_schedule.sass
index 30c416a..752ae35 100644
--- a/conference_main/static/conference_main/styles/_schedule.sass
+++ b/conference_main/static/conference_main/styles/_schedule.sass
@@ -1,3 +1,71 @@
+/* Theme-system mixins to make dynamic location colours contrast work with dark
+ * and light themes. */
+=theme-dark-schedule
+  --event-detail-location-color-l: 65%
+  --schedule-container-location-color-l: 65%
+  --schedule-filters-container-location-bg-color-l: 20%
+  --schedule-filters-container-location-color-l: 60%
+
+  .schedule-container
+    &.horizontal
+      .event
+        backdrop-filter: brightness(75%)
+
+        &:hover
+          backdrop-filter: brightness(80%)
+
+        /* Event favourited styles */
+        &:has(button[data-is-checked])
+          backdrop-filter: brightness(125%) saturate(200%)
+          color: var(--color-text-primary)
+
+          &:hover
+            backdrop-filter: brightness(130%) saturate(200%)
+
+          .event-header,
+          .event-speakers
+            // TODO: @web-assets consider adding variables colours grey shades
+            color: hsl(0, 0%, 75%)
+
+=theme-light-schedule
+  --event-detail-location-color-l: 35%
+  --schedule-container-location-color-l: 35%
+  --schedule-filters-container-location-bg-color-l: 10%
+  --schedule-filters-container-location-color-l: 50%
+
+  .schedule-container
+    &.horizontal
+      .event
+        backdrop-filter: brightness(110%)
+
+        &:hover
+          backdrop-filter: brightness(115%)
+
+        &:has(button[data-is-checked="data-is-checked"])
+          backdrop-filter: brightness(90%) saturate(400%)
+          color: var(--color-text-primary)
+
+          &:hover
+            backdrop-filter: brightness(95%) saturate(400%)
+
+          .event-header,
+          .event-speakers
+            color: hsl(0, 0%, 50%)
+
+\:root,
+[data-theme="light"]
+  +theme-light-schedule
+
+[data-theme="dark"]
+  +theme-dark-schedule
+
+@media (prefers-color-scheme: dark)
+  \:root
+    +theme-dark-schedule
+
+  [data-theme="light"]
+    +theme-light-schedule
+
 $col-time-width: 8%
 
 .schedule-container
@@ -68,7 +136,7 @@ $col-time-width: 8%
   &.toggle
     i
       border-radius: var(--spacer)
-      background-color: white
+      background-color: currentColor
       color: currentColor
       height: var(--spacer)
       +margin(1, right)
@@ -223,18 +291,18 @@ body.is-scrolled
     @include media-breakpoint-down(md)
       padding-top: 0.5 * $spacer
       padding-bottom: 0.5 * $spacer
-      border-bottom: var(--border-width) solid rgba(black, .05)
+      border-bottom: var(--border-width) solid var(--border-color)
 
   .row-rulers-lg
     @include media-breakpoint-up(lg)
-      border-top: var(--border-width) solid rgba(black, .05)
+      border-top: var(--border-width) solid var(--border-color)
       +padding(3, y)
 
   .col-rulers
     +padding(3, x)
 
     @include media-breakpoint-up(lg)
-      border-left: var(--border-width) solid rgba(black, .05)
+      border-left: var(--border-width) solid var(--border-color)
 
   .col-time
     @include media-breakpoint-up(lg)
@@ -412,6 +480,7 @@ body.is-scrolled
 
 .event
   +box-card
+
   display: flex
   flex-direction: column
   +margin(3, bottom)
@@ -419,7 +488,7 @@ body.is-scrolled
   transition: background-color var(--transition-speed) ease-in-out, opacity 250ms ease-in-out
 
   &:hover
-    background-color: white !important
+    background-color: var(--box-bg-color-hover)
     text-decoration: none
 
   &[data-filtered]
@@ -636,6 +705,10 @@ body.is-scrolled
   position: absolute
   right: 0
 
+  .event
+    background-color: transparent
+    transition: backdrop-filter var(--transition-speed)
+
   .schedule-filters-container
     +padding(2, y)
 
diff --git a/conference_main/static/conference_main/styles/main.sass b/conference_main/static/conference_main/styles/main.sass
index 540cdb7..d60edb3 100644
--- a/conference_main/static/conference_main/styles/main.sass
+++ b/conference_main/static/conference_main/styles/main.sass
@@ -2,6 +2,7 @@ $font-path: '/static/assets/fonts'
 
 // Import Web Assets.
 @import "../../../../assets_shared/src/styles/main.sass"
+@import "../../../../assets_shared/src/styles/_theme_system.sass"
 
 @import "_albums.sass"
 @import "_attendee.sass"
@@ -17,11 +18,15 @@ $font-path: '/static/assets/fonts'
 @import "_sponsors.sass"
 @import "_utils.sass"
 
-\:root
+\:root,
+html[data-theme="light"]
 	--body-color-bg: #e9ecef
 	--color-bg: var(--body-color-bg)
-	--navbar-bg: #1e1e1e
 
+	--box-bg-color-hover: white
+
+\:root
+	// TODO: check if component variables table colours are needed
 	--table-border-color: var(--color-bg-tertiary)
 	--table-row-bg-color: var(--color-bg-secondary)
 
@@ -38,6 +43,9 @@ $font-path: '/static/assets/fonts'
 	+media-sm
 		--page-with-header-content-offset: calc(var(--spacer) * 8)
 
+html[data-theme="dark"]
+	--box-bg-color-hover: var(--btn-color-bg-hover)
+
 body.is-scrolled
 	.navbar
 		box-shadow: none
@@ -252,6 +260,13 @@ button.going-star
 
 /* Web Assets overrides. */
 // TODO: check component forms in Web Assets v2
+.form-control
+	&:disabled,
+	&[readonly]
+		background-color: var(--input-color-bg)
+		color: var(--color-text-secondary)
+		pointer-events: none
+
 .form-group
 	display: block
 
diff --git a/conference_main/templates/conference_main/2023/flatpages/location.pug b/conference_main/templates/conference_main/2023/flatpages/location.pug
index 32945db..0e9f42b 100644
--- a/conference_main/templates/conference_main/2023/flatpages/location.pug
+++ b/conference_main/templates/conference_main/2023/flatpages/location.pug
@@ -3,7 +3,7 @@
 | {% block head_extra %}
 style.
   :root {
-    --bg-color-container: hsla(0, 0%, 100%, 0.9);
+    --bg-color-container: var(--box-bg-color);
     --bg-stripes-color-1: #5F1BED;
     --bg-stripes-color-2: #84BBDC;
     --bg-stripes-width: 75px;
diff --git a/conference_main/templates/conference_main/2023/presentations/speakers.pug b/conference_main/templates/conference_main/2023/presentations/speakers.pug
index 1e5e85d..705fff8 100644
--- a/conference_main/templates/conference_main/2023/presentations/speakers.pug
+++ b/conference_main/templates/conference_main/2023/presentations/speakers.pug
@@ -3,7 +3,7 @@
 | {% block head_extra %}
 style.
   :root {
-    --bg-color-container: hsla(0, 0%, 100%, 0.9);
+    --bg-color-container: var(--box-bg-color);
     --bg-color: #5F1BED;
     --bg-dots-color: #EFAA2A;
     --bg-dots-width: 300px;
diff --git a/conference_main/templates/conference_main/_navbar.pug b/conference_main/templates/conference_main/_navbar.pug
index e1f87df..e330ada 100644
--- a/conference_main/templates/conference_main/_navbar.pug
+++ b/conference_main/templates/conference_main/_navbar.pug
@@ -37,6 +37,10 @@ nav.nav-global(role='navigation')
 				| {% endif %}
 				| {% endif %}
 
+				li
+					button.js-toggle-theme-btn
+						i.i-adjust.js-toggle-theme-btn-icon
+
 				| {% include "conference_main/_navbar_menu_user.pug" %}
 
 				li
diff --git a/conference_main/templates/conference_main/base.pug b/conference_main/templates/conference_main/base.pug
index 55aaac6..2a29528 100644
--- a/conference_main/templates/conference_main/base.pug
+++ b/conference_main/templates/conference_main/base.pug
@@ -2,6 +2,13 @@
 | {% load pipeline %}
 | {% load static %}
 
+| {% block head_extra %}
+| {% verbatim %}
+script.
+	!function(){{const rootElement=document.documentElement;let themeValue;function getThemeValue(){themeValue=localStorage.getItem("dataTheme")}var data;getThemeValue(),themeValue&&(data=themeValue,getThemeValue(),rootElement.setAttribute("data-theme",data))}}();
+| {% endverbatim %}
+| {% endblock head_extra %}
+
 | {% block header %}
 | {% block jumbotron %}
 | {% include "conference_main/components/hero.pug" with show_logo=True show_date=True show_location=True show_overlay=True %}
diff --git a/conference_main/templates/conference_main/components/review_header_details.pug b/conference_main/templates/conference_main/components/review_header_details.pug
index 98b1d7b..fdfe95a 100644
--- a/conference_main/templates/conference_main/components/review_header_details.pug
+++ b/conference_main/templates/conference_main/components/review_header_details.pug
@@ -7,7 +7,7 @@
   | {% if object.status == 'accepted' %}
   div.ml-4
     small.text-muted.d-block Location
-    span(style="color: hsl(var(--location-hue-{{ object.location.slug }}), 50%, 50%);")
+    span(style="color: hsl(var(--location-hue-{{ object.location.slug }}), 80%, var(--event-detail-location-color-l));")
       | {% if object.location.slug %}
       | {{ object.location.slug | title }}
       | {% else %}
diff --git a/conference_main/templates/conference_main/head.pug b/conference_main/templates/conference_main/head.pug
index 947d333..3f56c15 100644
--- a/conference_main/templates/conference_main/head.pug
+++ b/conference_main/templates/conference_main/head.pug
@@ -1,7 +1,7 @@
 | {% load static %}
 | {% load pipeline %}
 !!! 5
-html(lang="en")
+html(data-theme="light", lang="en")
 	head
 		meta(charset='utf-8')
 		meta(name='viewport', content='width=device-width, initial-scale=1.0')
diff --git a/conference_main/templates/conference_main/presentations/detail.pug b/conference_main/templates/conference_main/presentations/detail.pug
index a4760f1..c1923d4 100644
--- a/conference_main/templates/conference_main/presentations/detail.pug
+++ b/conference_main/templates/conference_main/presentations/detail.pug
@@ -78,7 +78,7 @@ meta(name='twitter:image', content='{{request.scheme}}://{{request.META.HTTP_HOS
               ul.event-description
                 | {% if object.location.slug %}
                 li.event-location(
-                  style="color: hsl(var(--location-hue-{{ object.location.slug }}), 80%, 35%);")
+                  style="color: hsl(var(--location-hue-{{ object.location.slug }}), 80%, var(--event-detail-location-color-l));")
                   | {{ object.location.slug | upper }}
                 | {% endif %}
 
diff --git a/conference_main/templates/conference_main/presentations/schedule_horizontal.pug b/conference_main/templates/conference_main/presentations/schedule_horizontal.pug
index f9611f9..c170cad 100644
--- a/conference_main/templates/conference_main/presentations/schedule_horizontal.pug
+++ b/conference_main/templates/conference_main/presentations/schedule_horizontal.pug
@@ -63,7 +63,6 @@
             | {% for event in events %}
             a.event.js-time-slot(
               style="
-                background-color: hsl(var(--location-hue-{{ location }}), 60%, 97%);
                 left: calc(calc({{ event.start_time_in_minutes}} - {{ events_per_day_per_location_with_range.range_minutes.start }}) * 10px);
                 width: calc({{ event.duration_minutes}}px * {{ events_per_day_per_location_with_range.minute_to_pixel_multiplier }})"
               id="#event-{{ event.id }}",
diff --git a/conference_main/templates/conference_main/presentations/schedule_vertical.pug b/conference_main/templates/conference_main/presentations/schedule_vertical.pug
index ea514f0..54d100e 100644
--- a/conference_main/templates/conference_main/presentations/schedule_vertical.pug
+++ b/conference_main/templates/conference_main/presentations/schedule_vertical.pug
@@ -54,9 +54,9 @@
           }
 
           .event-location-{{ location.slug }} input:checked ~ label {
-            background-color: hsla(var(--location-hue-{{ location.slug }}), 50%, 50%, 10%);
+            background-color: hsla(var(--location-hue-{{ location.slug }}), 50%, 50%, var(--schedule-filters-container-location-bg-color-l));
             border-color: hsla(var(--location-hue-{{ location.slug }}), 50%, 50%, 20%);
-            color: hsl(var(--location-hue-{{ location.slug }}), 50%, 50%);
+            color: hsl(var(--location-hue-{{ location.slug }}), 50%, var(--schedule-filters-container-location-color-l));
           }
 
           .event-location-{{ location.slug }} input:checked ~ label:hover {
@@ -195,7 +195,7 @@
 
                 | {% if event.location.slug %}
                 li.event-location(
-                  style="color: hsl(var(--location-hue-{{ event.location.slug }}), 80%, 35%);")
+                  style="color: hsl(var(--location-hue-{{ event.location.slug }}), 80%, var(--schedule-container-location-color-l));")
                   | {{ event.location.slug | upper }}
                 | {% endif %}