diff --git a/app/soapbox/containers/soapbox.js b/app/soapbox/containers/soapbox.js
index 86190eb10..d4dccf7c0 100644
--- a/app/soapbox/containers/soapbox.js
+++ b/app/soapbox/containers/soapbox.js
@@ -87,7 +87,7 @@ class SoapboxMount extends React.PureComponent {
   }
 
   render() {
-    const { me, themeCss, reduceMotion, systemFont, dyslexicFont, demetricator, locale } = this.props;
+    const { me, themeCss, locale } = this.props;
     if (me === null) return null;
 
     const { localeData, messages } = getLocale();
@@ -100,11 +100,11 @@ class SoapboxMount extends React.PureComponent {
     //   return <Introduction />;
     // }
 
-    const bodyClass = classNames('app-body', {
-      'system-font': systemFont,
-      'no-reduce-motion': !reduceMotion,
-      'dyslexic': dyslexicFont,
-      'demetricator': demetricator,
+    const bodyClass = classNames('app-body', `theme-mode-${this.props.themeMode}`, {
+      'system-font': this.props.systemFont,
+      'no-reduce-motion': !this.props.reduceMotion,
+      'dyslexic': this.props.dyslexicFont,
+      'demetricator': this.props.demetricator,
     });
 
     return (
diff --git a/app/soapbox/reducers/theme.js b/app/soapbox/reducers/theme.js
index 42f379b68..d87297e88 100644
--- a/app/soapbox/reducers/theme.js
+++ b/app/soapbox/reducers/theme.js
@@ -3,45 +3,19 @@ import {
   THEME_GENERATE,
 } from '../actions/theme';
 import { Map as ImmutableMap } from 'immutable';
-import { brightness, hue, convert } from 'chromatism';
 
 const initialState = ImmutableMap();
 
-const modes = ImmutableMap({
-  light: ImmutableMap({
-    'primary-text-color': '#000000',
-    'primary-text-color-faint': 'rgba(0,0,0,0.6)',
-    'background-color': '#f2f2f2',
-    'foreground-color': '#ffffff',
-  }),
-  dark: ImmutableMap({
-    'primary-text-color': '#ffffff',
-    'primary-text-color-faint': 'rgba(255,255,255,0.6)',
-    'background-color': '#333333',
-    'foreground-color': '#222222',
-  }),
-});
-
-const cssrgba = (color, a) => {
-  const { r, g, b } = convert(color).rgb;
-  return `rgba(${[r, g, b, a].join(',')})`;
-};
-
-const makeContrast = (percent, color, mode) => {
-  percent = mode === 'light' ? -percent : percent;
-  return brightness(percent, color);
-};
+const hex2rgb = c => c.substr(1).match(/../g).map(x => + `0x${x}`);
 
 export const generateTheme = (brandColor, mode = 'light') => {
-  if (!brandColor) return modes.get(mode);
-  return modes.get(mode).merge(ImmutableMap({
-    'brand-color': brandColor,
-    'accent-color': brightness(10, hue(-3, brandColor).hex).hex,
-    'brand-color-faint': cssrgba(brandColor, 0.1),
-    'brand-color-med': cssrgba(brandColor, 0.2),
-    'highlight-text-color': makeContrast(5, brandColor, mode).hex,
-    'brand-color-hicontrast': makeContrast(15, brandColor, mode).hex,
-  }));
+  if (!brandColor) return false;
+  const [ r, g, b ] = hex2rgb(brandColor);
+  return ImmutableMap({
+    'brand-color-r': r,
+    'brand-color-g': g,
+    'brand-color-b': b,
+  });
 };
 
 export const setTheme = themeData => {
diff --git a/app/styles/application.scss b/app/styles/application.scss
index 0f5cfbe2d..3b5222fe1 100644
--- a/app/styles/application.scss
+++ b/app/styles/application.scss
@@ -1,4 +1,5 @@
 @import 'mixins';
+@import 'themes';
 @import 'variables';
 @import 'fonts';
 @import 'reset';
diff --git a/app/styles/themes.scss b/app/styles/themes.scss
new file mode 100644
index 000000000..f6be5fadc
--- /dev/null
+++ b/app/styles/themes.scss
@@ -0,0 +1,50 @@
+body {
+  --brand-color-rgb: var(--brand-color-r), var(--brand-color-g), var(--brand-color-b);
+  --brand-color: rgb(var(--brand-color-rgb));
+  --brand-color-faint: rgba(var(--brand-color-rgb), 0.1);
+  --brand-color-med: rgba(var(--brand-color-rgb), 0.2);
+  --accent-color: rgb(
+    calc(var(--brand-color-r) + 25),
+    calc(var(--brand-color-g) + 25),
+    calc(var(--brand-color-b) + 25)
+  );
+  --primary-text-color-rgb: var(--primary-text-color-r), var(--primary-text-color-g), var(--primary-text-color-b);
+  --primary-text-color: rgb(var(--primary-text-color-rgb));
+  --primary-text-color-faint: rgba(var(--primary-text-color-rgb), 0.6);
+}
+
+body.theme-mode-light {
+  --primary-text-color-r: 0;
+  --primary-text-color-g: 0;
+  --primary-text-color-b: 0;
+  --background-color: #f2f2f2;
+  --foreground-color: #ffffff;
+  --highlight-text-color: rgb(
+    calc(var(--brand-color-r) - 25),
+    calc(var(--brand-color-g) - 25),
+    calc(var(--brand-color-b) - 25)
+  );
+  --brand-color-hicontrast: rgb(
+    calc(var(--brand-color-r) - 50),
+    calc(var(--brand-color-g) - 50),
+    calc(var(--brand-color-b) - 50)
+  );
+}
+
+body.theme-mode-dark {
+  --primary-text-color-r: 255;
+  --primary-text-color-g: 255;
+  --primary-text-color-b: 255;
+  --background-color: #333333;
+  --foreground-color: #222222;
+  --highlight-text-color: rgb(
+    calc(var(--brand-color-r) + 25),
+    calc(var(--brand-color-g) + 25),
+    calc(var(--brand-color-b) + 25)
+  );
+  --brand-color-hicontrast: rgb(
+    calc(var(--brand-color-r) + 50),
+    calc(var(--brand-color-g) + 50),
+    calc(var(--brand-color-b) + 50)
+  );
+}
diff --git a/package.json b/package.json
index 9aafa764c..8e700dc41 100644
--- a/package.json
+++ b/package.json
@@ -56,7 +56,6 @@
     "babel-plugin-transform-react-remove-prop-types": "^0.4.24",
     "babel-runtime": "^6.26.0",
     "blurhash": "^1.0.0",
-    "chromatism": "^3.0.0",
     "classnames": "^2.2.5",
     "compression-webpack-plugin": "^3.0.0",
     "cross-env": "^6.0.0",
diff --git a/yarn.lock b/yarn.lock
index 378e1fd67..8185280d5 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2445,11 +2445,6 @@ chownr@^1.1.1:
   resolved "https://registry.yarnpkg.com/chownr/-/chownr-1.1.1.tgz#54726b8b8fff4df053c42187e801fb4412df1494"
   integrity sha512-j38EvO5+LHX84jlo6h4UzmOwi0UgW61WRyPtJz4qaadK5eY3BTS5TY/S1Stc3Uk2lIM6TPevAlULiEJwie860g==
 
-chromatism@^3.0.0:
-  version "3.0.0"
-  resolved "https://registry.yarnpkg.com/chromatism/-/chromatism-3.0.0.tgz#a7249d353c1e4f3577e444ac41171c4e2e624b12"
-  integrity sha1-pySdNTweTzV35ESsQRccTi5iSxI=
-
 chrome-trace-event@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/chrome-trace-event/-/chrome-trace-event-1.0.2.tgz#234090ee97c7d4ad1a2c4beae27505deffc608a4"