diff --git a/dist/breadcrumb.css b/dist/breadcrumb.css
new file mode 100644
index 0000000..43e7d1f
--- /dev/null
+++ b/dist/breadcrumb.css
@@ -0,0 +1,45 @@
+/* @bchen/ui — breadcrumb navigation
+ * Uses only tokens defined in dist/tokens.css.
+ * Companion to dist/tokens.css and dist/base.css. */
+
+.breadcrumb {
+  display: flex;
+  align-items: center;
+  flex-wrap: wrap;
+  gap: 0.25rem;
+  padding: 0.75rem 2rem 0;
+  font-size: 13px;
+  color: var(--fg-muted);
+}
+
+.breadcrumb a {
+  color: var(--fg-muted);
+  text-decoration: none;
+}
+
+.breadcrumb a:hover {
+  color: var(--fg);
+  text-decoration: underline;
+  text-underline-offset: 2px;
+}
+
+.breadcrumb a:focus-visible {
+  color: var(--fg);
+  outline: 2px solid var(--accent);
+  outline-offset: 2px;
+  border-radius: 2px;
+}
+
+.breadcrumb [aria-current="page"] {
+  color: var(--fg);
+  font-weight: 500;
+  text-decoration: none;
+  cursor: default;
+}
+
+.breadcrumb-sep {
+  color: var(--fg-muted);
+  user-select: none;
+  font-size: 11px;
+  opacity: 0.6;
+}
diff --git a/dist/sidebar.css b/dist/sidebar.css
new file mode 100644
index 0000000..fcba076
--- /dev/null
+++ b/dist/sidebar.css
@@ -0,0 +1,100 @@
+/* @bchen/ui — sidebar layout
+ * Uses only tokens defined in dist/tokens.css.
+ * Companion to dist/tokens.css and dist/base.css. */
+
+/* ── Desktop: two-column grid ─────────────────────────────────────────── */
+@media (min-width: 768px) {
+  body {
+    display: grid;
+    grid-template-columns: 200px 1fr;
+    grid-template-rows: 1fr;
+  }
+
+  .mobile-header { display: none; }
+
+  .sidebar {
+    display: flex;
+    flex-direction: column;
+    height: 100vh;
+    position: sticky;
+    top: 0;
+    border-right: var(--border);
+    background: var(--bg);
+    padding: 1rem 0;
+    overflow-y: auto;
+  }
+
+  .app-body {
+    min-width: 0;
+    display: flex;
+    flex-direction: column;
+    min-height: 100vh;
+  }
+}
+
+/* ── Mobile: sidebar hidden, top bar shown ─────────────────────────────── */
+@media (max-width: 767px) {
+  .sidebar { display: none; }
+  .mobile-header { display: flex; }
+  .app-body {
+    display: flex;
+    flex-direction: column;
+    flex: 1;
+  }
+}
+
+/* ── Sidebar components ────────────────────────────────────────────────── */
+.sidebar-brand {
+  padding: 0 1rem 1rem;
+  font-size: 13px;
+  font-weight: 600;
+  letter-spacing: 0.02em;
+}
+
+.sidebar-brand a {
+  text-decoration: none;
+  color: var(--fg);
+}
+
+.sidebar-nav {
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+  gap: 0.125rem;
+  padding: 0 0.5rem;
+}
+
+.nav-link {
+  padding: 0.5rem 0.75rem;
+  border-radius: var(--radius);
+  color: var(--fg);
+  text-decoration: none;
+  font-size: 14px;
+  transition: background 0.1s ease;
+}
+
+.nav-link:hover,
+.nav-link:focus-visible {
+  background: var(--bg-elevated);
+  outline: none;
+}
+
+.nav-link.nav-active {
+  font-weight: 600;
+  background: var(--bg-elevated);
+  color: var(--fg);
+}
+
+.sidebar-footer {
+  padding: 1rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+  border-top: 1px solid var(--border-color);
+  margin-top: auto;
+}
+
+.sidebar-user {
+  font-size: 11px;
+  color: var(--fg-muted);
+}
diff --git a/package.json b/package.json
index 28566fb..0bb0494 100644
--- a/package.json
+++ b/package.json
@@ -7,8 +7,10 @@
     "dist"
   ],
   "exports": {
-    "./tokens.css": "./dist/tokens.css",
-    "./base.css": "./dist/base.css"
+    "./tokens.css":     "./dist/tokens.css",
+    "./base.css":       "./dist/base.css",
+    "./sidebar.css":    "./dist/sidebar.css",
+    "./breadcrumb.css": "./dist/breadcrumb.css"
   },
   "scripts": {
     "test": "vitest run"
diff --git a/tests/breadcrumb.test.ts b/tests/breadcrumb.test.ts
new file mode 100644
index 0000000..adf92fe
--- /dev/null
+++ b/tests/breadcrumb.test.ts
@@ -0,0 +1,13 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'fs';
+
+const css = readFileSync(new URL('../dist/breadcrumb.css', import.meta.url), 'utf-8');
+
+describe('breadcrumb.css', () => {
+  it('is non-empty', () => { expect(css.length).toBeGreaterThan(0); });
+  it('references --fg', () => { expect(css).toContain('var(--fg)'); });
+  it('references --fg-muted', () => { expect(css).toContain('var(--fg-muted)'); });
+  it('styles aria-current="page"', () => { expect(css).toContain('[aria-current="page"]'); });
+  it('styles .breadcrumb-sep', () => { expect(css).toContain('.breadcrumb-sep'); });
+  it('styles .breadcrumb links', () => { expect(css).toContain('.breadcrumb a'); });
+});
diff --git a/tests/sidebar.test.ts b/tests/sidebar.test.ts
new file mode 100644
index 0000000..77e60d7
--- /dev/null
+++ b/tests/sidebar.test.ts
@@ -0,0 +1,17 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'fs';
+
+const css = readFileSync(new URL('../dist/sidebar.css', import.meta.url), 'utf-8');
+
+describe('sidebar.css', () => {
+  it('is non-empty', () => { expect(css.length).toBeGreaterThan(0); });
+  it('references --fg', () => { expect(css).toContain('var(--fg)'); });
+  it('references --bg', () => { expect(css).toContain('var(--bg)'); });
+  it('references --border', () => { expect(css).toMatch(/var\(--border/); });
+  it('references --radius', () => { expect(css).toContain('var(--radius)'); });
+  it('references --fg-muted', () => { expect(css).toContain('var(--fg-muted)'); });
+  it('includes responsive breakpoint at 768px', () => { expect(css).toContain('768px'); });
+  it('hides sidebar on mobile', () => { expect(css).toMatch(/\.sidebar\s*\{\s*display\s*:\s*none/); });
+  it('styles .nav-link', () => { expect(css).toContain('.nav-link'); });
+  it('styles .nav-active', () => { expect(css).toContain('nav-active'); });
+});