diff --git a/examples/v4-proto.tsx b/examples/v4-proto.tsx
index dcc2de0..4dcc9f1 100644
--- a/examples/v4-proto.tsx
+++ b/examples/v4-proto.tsx
@@ -2,22 +2,17 @@
 import { ReactNode, Fragment } from 'react';
 import { storiesOf } from '@storybook/react';
 
-import { jsx, css, createTheme, styled } from '@trousers/core';
-
-//@ts-ignore
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
-const theme = createTheme({
-    default: 'blue',
-    primary: 'red',
-});
+import { jsx, css, styled } from '@trousers/core';
 
 const styles = css('button', {
-    backgroundColor: 'var(--theme-default)',
+    backgroundColor: 'var(--default)',
     color: 'red',
-}).modifier('primary', {
-    backgroundColor: 'var(--theme-primary)',
-    color: 'blue',
-});
+})
+    .modifier('primary', {
+        backgroundColor: 'var(--primary)',
+        color: 'blue',
+    })
+    .theme({ default: 'blue', primary: 'red' });
 
 interface ButtonProps {
     primary?: boolean;
@@ -25,7 +20,7 @@ interface ButtonProps {
 }
 
 const Button = ({ primary, children }: ButtonProps) => (
-    <button css={styles} theme={theme} primary={primary}>
+    <button css={styles} primary={primary}>
         {children}
     </button>
 );
@@ -33,20 +28,15 @@ const Button = ({ primary, children }: ButtonProps) => (
 const StyledButton = styled.button(styles);
 const StyledButtonAlt = styled('button')(styles);
 
-storiesOf('v4', module)
-    .add('Default', () => (
-        <Fragment>
-            <Button>Themed Button!</Button>
-            <Button primary>Primary Themed Button!</Button>
-        </Fragment>
-    ))
-    .add('Styled', () => (
-        <Fragment>
-            <StyledButton> Styled, Themed Button!</StyledButton>
-            <StyledButton primary>Styled, Primary Themed Button!</StyledButton>
-            <StyledButtonAlt> Styled, Themed Button!</StyledButtonAlt>
-            <StyledButtonAlt primary>
-                Styled, Primary Themed Button!
-            </StyledButtonAlt>
-        </Fragment>
-    ));
+storiesOf('v4', module).add('Default', () => (
+    <Fragment>
+        <Button>Themed Button!</Button>
+        <Button primary>Primary Themed Button!</Button>
+        <StyledButton>Styled, Themed Button!</StyledButton>
+        <StyledButton primary>Styled, Primary Themed Button!</StyledButton>
+        <StyledButtonAlt>Styled, Themed Button!</StyledButtonAlt>
+        <StyledButtonAlt primary>
+            Styled, Primary Themed Button!
+        </StyledButtonAlt>
+    </Fragment>
+));
diff --git a/packages/core/src/css.ts b/packages/core/src/css.ts
index d81b5f6..2b2c525 100644
--- a/packages/core/src/css.ts
+++ b/packages/core/src/css.ts
@@ -2,12 +2,22 @@ import { CSSProperties } from 'react';
 import { Definition } from './types';
 import hash from './hash';
 
+function parseTheme(theme: Record<string, any>) {
+    return Object.keys(theme).reduce<CSSProperties>((accum, key) => {
+        // TODO: this can be nested - beware
+        //@ts-ignore
+        accum[`--${key}`] = theme[key];
+        return accum;
+    }, {});
+}
+
 function css(id: string, styles: CSSProperties) {
     const elementId = `${id}-${hash(JSON.stringify(styles))}`;
     const styleMap: Definition[] = [
         {
             id,
             className: elementId,
+            type: 'element',
             styles,
         },
     ];
@@ -17,12 +27,23 @@ function css(id: string, styles: CSSProperties) {
         modifier: (modifierId: string, modifierStyles: CSSProperties) => {
             styleMap.push({
                 id: modifierId,
+                type: 'modifier',
                 className: `${elementId}--${modifierId}-${hash(
                     JSON.stringify(modifierStyles),
                 )}`,
                 styles: modifierStyles,
             });
 
+            return self;
+        },
+        theme: (theme: Record<string, any>) => {
+            styleMap.push({
+                id: `theme-${id}`,
+                type: 'theme',
+                className: `theme-${id}`,
+                styles: parseTheme(theme),
+            });
+
             return self;
         },
     };
diff --git a/packages/core/src/global-types.ts b/packages/core/src/global-types.ts
index 12e16f8..fc061fb 100644
--- a/packages/core/src/global-types.ts
+++ b/packages/core/src/global-types.ts
@@ -3,8 +3,7 @@ import { Collector } from './css';
 declare module 'react' {
     interface DOMAttributes<T> {
         css?: ReturnType<Collector>;
-        theme?: string;
-        primary?: boolean;
+        primary?: boolean; // TODO: Figure this one out
     }
 }
 
@@ -12,8 +11,7 @@ declare global {
     namespace JSX {
         interface IntrinsicAttributes {
             css?: ReturnType<Collector>;
-            theme?: string;
-            primary?: boolean;
+            primary?: boolean; // TODO: Figure this one out
         }
     }
 }
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index abe27c7..3774a5e 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -1,4 +1,3 @@
 export { default as css } from './css';
-export { default as createTheme } from './theme';
 export { default as jsx } from './jsx';
 export { default as styled } from './styled';
diff --git a/packages/core/src/jsx.tsx b/packages/core/src/jsx.tsx
index 047495d..11bc6cc 100644
--- a/packages/core/src/jsx.tsx
+++ b/packages/core/src/jsx.tsx
@@ -31,7 +31,7 @@ const jsx = <
     const { css, theme, primary, ...rest } = props;
     const definitions = css
         ._get()
-        .filter(({ id }, index) => index === 0 || !!(props as any)[id]);
+        .filter(({ id, type }) => type !== 'modifier' || !!(props as any)[id]);
     const classes = definitions
         .map(({ className }) => className)
         .join(' ')
@@ -43,14 +43,14 @@ const jsx = <
         const styleSheet = sheet(headElement, 'data-trousers');
 
         definitions
-            .filter(({ className }) => !styleSheet.has(`.${className}`))
+            .filter(({ className }) => !styleSheet.has(className))
             .forEach(({ className, styles }) => {
-                console.log(styles);
-
                 if (!styleSheet.has(className)) {
                     const styleString = parse(styles);
                     const prefixedStyles = prefix(`.${className}`, styleString);
 
+                    console.log('mounting', className);
+
                     styleSheet.mount(className, prefixedStyles, false);
                 }
             });
diff --git a/packages/core/src/sheet.ts b/packages/core/src/sheet.ts
index 86c154c..30bfe57 100644
--- a/packages/core/src/sheet.ts
+++ b/packages/core/src/sheet.ts
@@ -39,6 +39,7 @@ const sheet = (targetEl: HTMLElement, attributeId: string) => {
     const has = (id: string) => styleMap.has(id);
 
     const mount = (id: string, styles: string, isGlobal?: boolean) => {
+        // TODO: maybe a map isn't the best thing to use here
         styleMap.set(id, '');
 
         try {
diff --git a/packages/core/src/theme.ts b/packages/core/src/theme.ts
deleted file mode 100644
index 81ea54b..0000000
--- a/packages/core/src/theme.ts
+++ /dev/null
@@ -1,7 +0,0 @@
-// @ts-ignore
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
-function createTheme(theme: Record<string, any>) {
-    return '';
-}
-
-export default createTheme;
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index 5b99b3d..d52bfc2 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -2,6 +2,7 @@ import { CSSProperties } from 'react';
 
 export interface Definition {
     id: string;
+    type: 'element' | 'modifier' | 'theme';
     className: string;
     styles: CSSProperties;
 }