diff --git a/app/assets/stylesheets/variables.scss b/app/assets/stylesheets/variables.scss
index e779339cd..a9b08df4d 100644
--- a/app/assets/stylesheets/variables.scss
+++ b/app/assets/stylesheets/variables.scss
@@ -31,3 +31,34 @@ $shadow: 1px 2px 4px 0 rgba(0, 0, 0, 0.18);
 $light-shadow: 1px 2px 4px 0 rgba(0, 0, 0, 0.1);
 $dark-shadow: 1px 2px 4px 0 rgba(0, 0, 0, 0.25);
 $bold-shadow: 3px 3px 0px darken($light-medium-gray, 13%);
+
+body {
+  &.night-theme {
+    background-color: black !important;
+
+    &,
+    & .highlight,
+    & iframe,
+    & video {
+      -webkit-filter: invert(100%);
+      filter: invert(100%);
+    }
+
+    & * {
+      background-blend-mode: difference;
+    }
+
+    img,
+    .image.image {
+      -webkit-transition: -webkit-filter 0.5s ease-in, filter 0.5s ease-in;
+      -webkit-filter: invert(100%) grayscale(100%);
+      transition: -webkit-filter 0.5s ease-in, filter 0.5s ease-in;
+      filter: invert(100%) grayscale(100%);
+
+      &:hover {
+        -webkit-filter: invert(100%) grayscale(0%);
+        filter: invert(100%) grayscale(0%);
+      }
+    }
+  }
+}