diff --git a/packages/kit/src/components/internal/Button.tsx b/packages/kit/src/components/internal/Button.tsx
index b0848fb77..06a34fd52 100644
--- a/packages/kit/src/components/internal/Button.tsx
+++ b/packages/kit/src/components/internal/Button.tsx
@@ -14,18 +14,20 @@ export const Button: React.FC<ButtonProps> = ({
   ...props
 }) => {
   const {colors} = useTheme()
+  const buttonVariant = colors[variant]
 
   const baseStyles = "px-4 py-2 rounded-md font-medium transition-colors"
-  const variantStyles = {
-    primary: colors.primary,
-    secondary: colors.secondary,
-    outline: colors.outline,
-    link: colors.link,
-  }
+
+  const variantClasses = twMerge(
+    buttonVariant.background,
+    buttonVariant.text,
+    buttonVariant.hover,
+    buttonVariant.border
+  )
 
   return (
     <HeadlessButton
-      className={twMerge(baseStyles, variantStyles[variant], className)}
+      className={twMerge(baseStyles, variantClasses, className)}
       {...props}
     />
   )
diff --git a/packages/kit/src/core/theme.tsx b/packages/kit/src/core/theme.tsx
index 9746d5e3b..0fdd72b20 100644
--- a/packages/kit/src/core/theme.tsx
+++ b/packages/kit/src/core/theme.tsx
@@ -1,10 +1,17 @@
 import React, {createContext, useContext} from "react"
 
+export type ButtonVariant = {
+  background: string
+  text: string
+  hover: string
+  border?: string
+}
+
 export type ThemeColors = {
-  primary: string
-  secondary: string
-  outline: string
-  link: string
+  primary: ButtonVariant
+  secondary: ButtonVariant
+  outline: ButtonVariant
+  link: ButtonVariant
 }
 
 export type Theme = {
@@ -13,32 +20,74 @@ export type Theme = {
 
 const defaultTheme: Theme = {
   colors: {
-    primary: "bg-slate-900 text-white hover:bg-slate-800",
-    secondary: "bg-slate-100 text-slate-900 hover:bg-slate-200",
-    outline:
-      "bg-transparent border border-slate-200 text-slate-900 hover:bg-slate-100",
-    link: "bg-transparent text-black hover:underline hover:text-black",
+    primary: {
+      background: "bg-slate-900",
+      text: "text-white",
+      hover: "hover:bg-slate-800",
+      border: undefined,
+    },
+    secondary: {
+      background: "bg-slate-100",
+      text: "text-slate-900",
+      hover: "hover:bg-slate-200",
+      border: undefined,
+    },
+    outline: {
+      background: "bg-transparent",
+      text: "text-slate-900",
+      hover: "hover:bg-slate-100",
+      border: "border border-slate-200",
+    },
+    link: {
+      background: "bg-transparent",
+      text: "text-slate-900",
+      hover: "hover:underline",
+      border: undefined,
+    },
   },
 }
 
 const ThemeContext = createContext<Theme>(defaultTheme)
 export const useTheme = () => useContext(ThemeContext)
 
+type DeepPartial<T> = {
+  [P in keyof T]?: T[P] extends object ? DeepPartial<T[P]> : T[P]
+}
+
 type ThemeProviderProps = React.PropsWithChildren<{
-  theme?: Partial<Theme>
+  theme?: DeepPartial<Theme>
 }>
 
+const deepMerge = <T extends object>(target: T, source?: DeepPartial<T>): T => {
+  if (!source) return target
+  const result = {...target}
+
+  Object.keys(source).forEach(key => {
+    const targetValue = target[key as keyof T]
+    const sourceValue = source[key as keyof DeepPartial<T>]
+
+    if (
+      sourceValue &&
+      typeof sourceValue === "object" &&
+      targetValue &&
+      typeof targetValue === "object"
+    ) {
+      result[key as keyof T] = deepMerge(
+        targetValue as object,
+        sourceValue as object
+      ) as T[keyof T]
+    } else if (sourceValue !== undefined) {
+      result[key as keyof T] = sourceValue as T[keyof T]
+    }
+  })
+
+  return result
+}
+
 export const ThemeProvider = ({
   theme: customTheme,
   children,
 }: ThemeProviderProps) => {
-  const theme = {
-    ...defaultTheme,
-    ...customTheme,
-    colors: {
-      ...defaultTheme.colors,
-      ...customTheme?.colors,
-    },
-  }
+  const theme = deepMerge(defaultTheme, customTheme)
   return <ThemeContext.Provider value={theme}>{children}</ThemeContext.Provider>
 }
diff --git a/packages/kit/src/provider/FlowProvider.tsx b/packages/kit/src/provider/FlowProvider.tsx
index 6d515fa4a..92221db77 100644
--- a/packages/kit/src/provider/FlowProvider.tsx
+++ b/packages/kit/src/provider/FlowProvider.tsx
@@ -4,13 +4,14 @@ import {FlowConfig, FlowConfigContext} from "../core/context"
 import {DefaultOptions, QueryClient} from "@tanstack/react-query"
 import {FlowQueryClientProvider} from "./FlowQueryClient"
 import {deepEqual} from "../utils/deepEqual"
-import {ThemeProvider} from "../core/theme"
+import {ThemeProvider, Theme} from "../core/theme"
 import tailwindStyles from "../styles/tailwind.css"
 
 interface FlowProviderProps {
   config?: FlowConfig
   queryClient?: QueryClient
   flowJson?: Record<string, any>
+  theme?: Partial<Theme>
 }
 
 const mappings: Array<{fcl: string; typed: keyof FlowConfig}> = [
@@ -93,6 +94,7 @@ export function FlowProvider({
   config: initialConfig = {},
   queryClient: _queryClient,
   flowJson,
+  theme: customTheme,
   children,
 }: PropsWithChildren<FlowProviderProps>) {
   const [queryClient] = useState<QueryClient>(
@@ -144,7 +146,7 @@ export function FlowProvider({
     <FlowQueryClientProvider queryClient={queryClient}>
       <FlowConfigContext.Provider value={flowConfig}>
         <style>{tailwindStyles}</style>
-        <ThemeProvider>{children}</ThemeProvider>
+        <ThemeProvider theme={customTheme}>{children}</ThemeProvider>
       </FlowConfigContext.Provider>
     </FlowQueryClientProvider>
   )