diff --git a/.github/workflows/frontend.yml b/.github/workflows/frontend.yml
index 35fec7c..dd8f539 100644
--- a/.github/workflows/frontend.yml
+++ b/.github/workflows/frontend.yml
@@ -3,6 +3,7 @@ on:
   pull_request:
     branches: [ dev ]
     paths:
+      - 'app/**'
       - 'package.json'
       - 'tsconfig.json'
       - 'bun.lockb'
diff --git a/app/fragments/window/sidebar/index.tsx b/app/fragments/window/sidebar/index.tsx
new file mode 100644
index 0000000..30c440b
--- /dev/null
+++ b/app/fragments/window/sidebar/index.tsx
@@ -0,0 +1,5 @@
+import { sidebar } from './styles.css.ts'
+
+export function Sidebar() {
+	return <div className={sidebar}></div>
+}
diff --git a/app/fragments/window/sidebar/styles.css.ts b/app/fragments/window/sidebar/styles.css.ts
new file mode 100644
index 0000000..7de4392
--- /dev/null
+++ b/app/fragments/window/sidebar/styles.css.ts
@@ -0,0 +1,6 @@
+import { style } from '@vanilla-extract/css'
+
+export const sidebar = style({
+	width: '4rem',
+	position: 'relative',
+})
diff --git a/app/root.tsx b/app/root.tsx
index f0aa73e..a1fea4c 100644
--- a/app/root.tsx
+++ b/app/root.tsx
@@ -1,8 +1,17 @@
-import                 '&theme/preflight.css.ts'
-import                 '&theme/provider.tsx'
+import                  '&theme/preflight.css.ts'
+import                  '&theme/provider.tsx'
 
-import { Button } from '&ui/button'
+import { Sidebar } from '&fragments/window/sidebar'
+import { Box }     from '&ui/layout'
+import { Row }     from '&ui/layout'
 
 export function Root() {
-	return <Button style={{ margin: '50px' }}>Launch</Button>
+	return (
+		<Row>
+			<Sidebar />
+			<Box bg='background' roundedLeft='m'>
+				{/* TODO */}
+			</Box>
+		</Row>
+	)
 }
diff --git a/app/shared/nanolib.ts b/app/shared/nanolib.ts
new file mode 100644
index 0000000..78a8b7a
--- /dev/null
+++ b/app/shared/nanolib.ts
@@ -0,0 +1,31 @@
+const { entries } = Object
+
+export type Leaves<T> = T extends object
+	? { [K in keyof T]: `${Exclude<K, symbol>}${Leaves<T[K]> extends never ? '' : `.${Leaves<T[K]>}`}` }[keyof T]
+	: never
+
+type PathAccess<T, P extends string> = P extends `${infer K}.${infer R}`
+	? K extends keyof T
+		? PathAccess<T[K], R>
+		: never
+	: P extends keyof T
+		? T[P]
+		: never
+
+export function leaves<T extends object>(target: T, prefix: string[] = []): Leaves<T>[] {
+	const list = []
+
+	for (const [key, value] of entries(target)) {
+		if (typeof value === 'object') {
+			list.push(...leaves(value, [...prefix, key]))
+		} else {
+			list.push([...prefix, key].join('.'))
+		}
+	}
+
+	return list as Leaves<T>[]
+}
+
+export function pathAccess<T extends object, P extends Leaves<T>>(target: T, path: P) {
+	return path.split('.').reduce((a, c) => Reflect.get(a as object, c), target) as PathAccess<T, P>
+}
diff --git a/app/theme/base.css.ts b/app/theme/base.css.ts
index 7afc3f9..a999e68 100644
--- a/app/theme/base.css.ts
+++ b/app/theme/base.css.ts
@@ -1,7 +1,6 @@
-import      { clashDisplay } from '&theme/fonts.css.ts'
-import      { manrope }      from '&theme/fonts.css.ts'
-import      { geistMono }    from '&theme/fonts.css.ts'
-
+import      { clashDisplay } from './fonts.css.ts'
+import      { manrope }      from './fonts.css.ts'
+import      { geistMono }    from './fonts.css.ts'
 import type { ThemePart }    from './shared.ts'
 import type { vars }         from './vars.css.ts'
 
diff --git a/app/theme/dark.css.ts b/app/theme/dark.css.ts
index 91202b6..d0490d2 100644
--- a/app/theme/dark.css.ts
+++ b/app/theme/dark.css.ts
@@ -17,6 +17,7 @@ export const theme = createTheme(vars, {
 			readable: '#18181b',
 		},
 		gray: {
+			surface: '#212124',
 			input: '#3b3a38',
 		},
 	},
diff --git a/app/theme/light.css.ts b/app/theme/light.css.ts
index eb3e75c..fb23810 100644
--- a/app/theme/light.css.ts
+++ b/app/theme/light.css.ts
@@ -17,6 +17,7 @@ export const theme = createTheme(vars, {
 			readable: '#f9f1e9',
 		},
 		gray: {
+			surface: '#ece3d9',
 			input: '#d2cfc9',
 		},
 	},
diff --git a/app/theme/preflight.css.ts b/app/theme/preflight.css.ts
index e360a82..30e1ca2 100644
--- a/app/theme/preflight.css.ts
+++ b/app/theme/preflight.css.ts
@@ -24,8 +24,8 @@ globalStyle('*', {
 globalStyle('body', {
 	'@layer': {
 		[preflight]: {
-			minHeight: '100vh',
-			backgroundColor: vars.color.background,
+			height: '100vh',
+			backgroundColor: vars.color.gray.surface,
 			fontFamily: vars.font.sans,
 			fontSize: '87.5%',
 			transition: `all ${vars.transition.duration.l} ${vars.transition.timing}`,
@@ -55,3 +55,8 @@ globalStyle('img', {
 		},
 	},
 })
+
+globalStyle('#root', {
+	height: '100vh',
+	display: 'flex',
+})
diff --git a/app/theme/vars.css.ts b/app/theme/vars.css.ts
index 7ac5ced..b8df049 100644
--- a/app/theme/vars.css.ts
+++ b/app/theme/vars.css.ts
@@ -1,4 +1,8 @@
-import { createThemeContract } from '@vanilla-extract/css'
+import type { style }               from '@vanilla-extract/css'
+import      { createThemeContract } from '@vanilla-extract/css'
+
+import      { leaves }              from '&shared/nanolib.ts'
+import      { pathAccess }          from '&shared/nanolib.ts'
 
 const typography = {
 	size: null,
@@ -20,6 +24,7 @@ export const vars = createThemeContract({
 			readable: null,
 		},
 		gray: {
+			surface: null,
 			input: null,
 		},
 	},
@@ -73,3 +78,14 @@ export const vars = createThemeContract({
 		},
 	},
 })
+
+export function mapVars<T extends object>(vars: T, fn: (val: keyof T) => Parameters<typeof style>[0]) {
+	return Object.fromEntries(Object.entries(vars).map(([key, value]) => [key, fn(value)])) as Record<
+		keyof T,
+		Parameters<typeof style>[0]
+	>
+}
+
+export function mapVarsPath<T extends object>(vars: T, fn: (val: string) => Parameters<typeof style>[0]) {
+	return Object.fromEntries(leaves(vars).map((path) => [path, fn(pathAccess(vars, path) as string)]))
+}
diff --git a/app/ui/layout/index.tsx b/app/ui/layout/index.tsx
new file mode 100644
index 0000000..024e3d9
--- /dev/null
+++ b/app/ui/layout/index.tsx
@@ -0,0 +1,26 @@
+import      { clsx }        from 'clsx'
+
+import type { LayoutProps } from './shared.ts'
+import      { useStyle }    from './shared.ts'
+import      { box }         from './styles.css.ts'
+import      { col }         from './styles.css.ts'
+import      { row }         from './styles.css.ts'
+
+export function Row(props: LayoutProps) {
+	const { style, rest } = useStyle(props)
+	return <div {...rest} className={clsx(row, style)} />
+}
+
+export function Col(props: LayoutProps) {
+	const { style, rest } = useStyle(props)
+	return <div {...rest} className={clsx(col, style)} />
+}
+
+export type BoxProps = Omit<LayoutProps, 'gap' | 'grow'>
+
+export function Box(props: BoxProps) {
+	const { style, rest } = useStyle(props)
+	return <div {...rest} className={clsx(box, style)} />
+}
+
+export type { LayoutProps }
diff --git a/app/ui/layout/shared.ts b/app/ui/layout/shared.ts
new file mode 100644
index 0000000..9a2248a
--- /dev/null
+++ b/app/ui/layout/shared.ts
@@ -0,0 +1,32 @@
+import type { ComponentProps } from 'react'
+
+import      { clsx }           from 'clsx'
+
+import type { Leaves }         from '&shared/nanolib.ts'
+import type { vars }           from '&theme/vars.css.ts'
+import      { variants }       from '&ui/layout/styles.css.ts'
+
+export type LayoutProps = ComponentProps<'div'> & {
+	gap?: keyof typeof vars.space
+	p?: keyof typeof vars.space
+	bg?: Leaves<typeof vars.color>
+	rounded?: keyof typeof vars.rounded
+	roundedLeft?: keyof typeof vars.rounded
+	grow?: boolean
+}
+
+export function useStyle(props: LayoutProps) {
+	const { gap, p, bg, grow, rounded, roundedLeft, ...rest } = props
+
+	return {
+		style: clsx(
+			gap && variants.gap[gap],
+			p && variants.p[p],
+			bg && variants.bg[bg],
+			grow && variants.grow.true,
+			rounded && variants.rounded[rounded],
+			roundedLeft && variants.roundedLeft[roundedLeft],
+		),
+		rest,
+	}
+}
diff --git a/app/ui/layout/styles.css.ts b/app/ui/layout/styles.css.ts
new file mode 100644
index 0000000..57de793
--- /dev/null
+++ b/app/ui/layout/styles.css.ts
@@ -0,0 +1,54 @@
+import { style }         from '@vanilla-extract/css'
+import { styleVariants } from '@vanilla-extract/css'
+
+import { mapVars }       from '&theme/vars.css.ts'
+import { mapVarsPath }   from '&theme/vars.css.ts'
+import { vars }          from '&theme/vars.css.ts'
+
+const base = style({
+	display: 'flex',
+	transitionProperty: 'all',
+	transitionDuration: vars.transition.duration.m,
+	transitionTimingFunction: vars.transition.timing,
+})
+
+export const variants = {
+	gap: styleVariants(mapVars(vars.space, (gap) => ({ gap }))),
+	p: styleVariants(mapVars(vars.space, (padding) => ({ padding }))),
+	bg: styleVariants(mapVarsPath(vars.color, (backgroundColor) => ({ backgroundColor }))),
+	rounded: styleVariants(mapVars(vars.rounded, (borderRadius) => ({ borderRadius }))),
+	roundedLeft: styleVariants(
+		mapVars(vars.rounded, (radius) => ({
+			borderTopLeftRadius: radius,
+			borderBottomLeftRadius: radius,
+		})),
+	),
+	grow: styleVariants({
+		true: {
+			flexGrow: 1,
+		},
+	}),
+}
+
+export const row = style([
+	base,
+	{
+		width: '100%',
+		flexDirection: 'row',
+	},
+])
+
+export const col = style([
+	base,
+	{
+		height: '100%',
+		flexDirection: 'column',
+	},
+])
+
+export const box = style([
+	base,
+	{
+		flexGrow: 1,
+	},
+])