diff --git a/AGENTS.md b/AGENTS.md
index 4d3c786..45c7b42 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -24,6 +24,19 @@ Run these after implementing to get immediate feedback:
 - Path aliases: `@/*` maps to `./src/*`
 - Pre-commit hooks: Biome lint + Vitest tests via Lefthook
 
+## Database Setup
+
+PocketBase requires these collections: `users`, `period_logs`, `dailyLogs`.
+
+To create missing collections:
+```bash
+POCKETBASE_ADMIN_EMAIL=admin@example.com \
+POCKETBASE_ADMIN_PASSWORD=yourpassword \
+pnpm db:setup
+```
+
+The script reads `NEXT_PUBLIC_POCKETBASE_URL` from your environment and creates any missing collections. It's safe to run multiple times - existing collections are skipped.
+
 ## Codebase Patterns
 
 - TDD required: Write tests before implementation
diff --git a/package.json b/package.json
index 349ca01..01e68fe 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,8 @@
     "lint": "biome check .",
     "lint:fix": "biome check --write .",
     "test": "vitest",
-    "test:run": "vitest run"
+    "test:run": "vitest run",
+    "db:setup": "npx tsx scripts/setup-db.ts"
   },
   "dependencies": {
     "class-variance-authority": "^0.7.1",
diff --git a/scripts/setup-db.test.ts b/scripts/setup-db.test.ts
new file mode 100644
index 0000000..3d41a9f
--- /dev/null
+++ b/scripts/setup-db.test.ts
@@ -0,0 +1,164 @@
+// ABOUTME: Tests for the database setup script that creates PocketBase collections.
+// ABOUTME: Verifies collection definitions and setup logic without hitting real PocketBase.
+import { describe, expect, it, vi } from "vitest";
+
+import {
+  DAILY_LOGS_COLLECTION,
+  getExistingCollectionNames,
+  getMissingCollections,
+  PERIOD_LOGS_COLLECTION,
+} from "./setup-db";
+
+describe("PERIOD_LOGS_COLLECTION", () => {
+  it("has correct name", () => {
+    expect(PERIOD_LOGS_COLLECTION.name).toBe("period_logs");
+  });
+
+  it("has required fields", () => {
+    const fieldNames = PERIOD_LOGS_COLLECTION.fields.map((f) => f.name);
+    expect(fieldNames).toContain("user");
+    expect(fieldNames).toContain("startDate");
+    expect(fieldNames).toContain("predictedDate");
+  });
+
+  it("has user field as relation to users", () => {
+    const userField = PERIOD_LOGS_COLLECTION.fields.find(
+      (f) => f.name === "user",
+    );
+    expect(userField?.type).toBe("relation");
+    expect(userField?.collectionId).toBe("users");
+    expect(userField?.maxSelect).toBe(1);
+    expect(userField?.cascadeDelete).toBe(true);
+  });
+
+  it("has startDate as required date", () => {
+    const startDateField = PERIOD_LOGS_COLLECTION.fields.find(
+      (f) => f.name === "startDate",
+    );
+    expect(startDateField?.type).toBe("date");
+    expect(startDateField?.required).toBe(true);
+  });
+
+  it("has predictedDate as optional date", () => {
+    const predictedDateField = PERIOD_LOGS_COLLECTION.fields.find(
+      (f) => f.name === "predictedDate",
+    );
+    expect(predictedDateField?.type).toBe("date");
+    expect(predictedDateField?.required).toBe(false);
+  });
+});
+
+describe("DAILY_LOGS_COLLECTION", () => {
+  it("has correct name", () => {
+    expect(DAILY_LOGS_COLLECTION.name).toBe("dailyLogs");
+  });
+
+  it("has all required fields", () => {
+    const fieldNames = DAILY_LOGS_COLLECTION.fields.map((f) => f.name);
+
+    // Core fields
+    expect(fieldNames).toContain("user");
+    expect(fieldNames).toContain("date");
+    expect(fieldNames).toContain("cycleDay");
+    expect(fieldNames).toContain("phase");
+
+    // Garmin biometric fields
+    expect(fieldNames).toContain("bodyBatteryCurrent");
+    expect(fieldNames).toContain("bodyBatteryYesterdayLow");
+    expect(fieldNames).toContain("hrvStatus");
+    expect(fieldNames).toContain("weekIntensityMinutes");
+
+    // Decision fields
+    expect(fieldNames).toContain("phaseLimit");
+    expect(fieldNames).toContain("remainingMinutes");
+    expect(fieldNames).toContain("trainingDecision");
+    expect(fieldNames).toContain("decisionReason");
+    expect(fieldNames).toContain("notificationSentAt");
+  });
+
+  it("has user field as relation to users", () => {
+    const userField = DAILY_LOGS_COLLECTION.fields.find(
+      (f) => f.name === "user",
+    );
+    expect(userField?.type).toBe("relation");
+    expect(userField?.collectionId).toBe("users");
+    expect(userField?.maxSelect).toBe(1);
+    expect(userField?.cascadeDelete).toBe(true);
+  });
+
+  it("has trainingDecision as required text", () => {
+    const field = DAILY_LOGS_COLLECTION.fields.find(
+      (f) => f.name === "trainingDecision",
+    );
+    expect(field?.type).toBe("text");
+    expect(field?.required).toBe(true);
+  });
+});
+
+describe("getExistingCollectionNames", () => {
+  it("extracts collection names from PocketBase response", async () => {
+    const mockPb = {
+      collections: {
+        getFullList: vi
+          .fn()
+          .mockResolvedValue([
+            { name: "users" },
+            { name: "period_logs" },
+            { name: "_superusers" },
+          ]),
+      },
+    };
+
+    // biome-ignore lint/suspicious/noExplicitAny: test mock
+    const names = await getExistingCollectionNames(mockPb as any);
+
+    expect(names).toEqual(["users", "period_logs", "_superusers"]);
+  });
+
+  it("returns empty array when no collections exist", async () => {
+    const mockPb = {
+      collections: {
+        getFullList: vi.fn().mockResolvedValue([]),
+      },
+    };
+
+    // biome-ignore lint/suspicious/noExplicitAny: test mock
+    const names = await getExistingCollectionNames(mockPb as any);
+
+    expect(names).toEqual([]);
+  });
+});
+
+describe("getMissingCollections", () => {
+  it("returns both collections when none exist", () => {
+    const existing = ["users"];
+    const missing = getMissingCollections(existing);
+
+    expect(missing).toHaveLength(2);
+    expect(missing.map((c) => c.name)).toContain("period_logs");
+    expect(missing.map((c) => c.name)).toContain("dailyLogs");
+  });
+
+  it("returns only dailyLogs when period_logs exists", () => {
+    const existing = ["users", "period_logs"];
+    const missing = getMissingCollections(existing);
+
+    expect(missing).toHaveLength(1);
+    expect(missing[0].name).toBe("dailyLogs");
+  });
+
+  it("returns only period_logs when dailyLogs exists", () => {
+    const existing = ["users", "dailyLogs"];
+    const missing = getMissingCollections(existing);
+
+    expect(missing).toHaveLength(1);
+    expect(missing[0].name).toBe("period_logs");
+  });
+
+  it("returns empty array when all collections exist", () => {
+    const existing = ["users", "period_logs", "dailyLogs"];
+    const missing = getMissingCollections(existing);
+
+    expect(missing).toHaveLength(0);
+  });
+});
diff --git a/scripts/setup-db.ts b/scripts/setup-db.ts
new file mode 100644
index 0000000..33d17cc
--- /dev/null
+++ b/scripts/setup-db.ts
@@ -0,0 +1,287 @@
+// ABOUTME: Database setup script for creating PocketBase collections.
+// ABOUTME: Run with: POCKETBASE_ADMIN_EMAIL=... POCKETBASE_ADMIN_PASSWORD=... pnpm db:setup
+import PocketBase from "pocketbase";
+
+/**
+ * Collection field definition for PocketBase.
+ * For relation fields, collectionId/maxSelect/cascadeDelete are top-level properties.
+ */
+interface CollectionField {
+  name: string;
+  type: string;
+  required?: boolean;
+  // Relation field properties (top-level, not in options)
+  collectionId?: string;
+  maxSelect?: number;
+  cascadeDelete?: boolean;
+}
+
+/**
+ * Collection definition for PocketBase.
+ */
+interface CollectionDefinition {
+  name: string;
+  type: string;
+  fields: CollectionField[];
+}
+
+/**
+ * Period logs collection schema - tracks menstrual cycle start dates.
+ * Note: collectionId will be resolved at runtime to the actual users collection ID.
+ */
+export const PERIOD_LOGS_COLLECTION: CollectionDefinition = {
+  name: "period_logs",
+  type: "base",
+  fields: [
+    {
+      name: "user",
+      type: "relation",
+      required: true,
+      collectionId: "users", // Will be resolved to actual ID at runtime
+      maxSelect: 1,
+      cascadeDelete: true,
+    },
+    {
+      name: "startDate",
+      type: "date",
+      required: true,
+    },
+    {
+      name: "predictedDate",
+      type: "date",
+      required: false,
+    },
+  ],
+};
+
+/**
+ * Daily logs collection schema - daily training snapshots with biometrics.
+ * Note: collectionId will be resolved at runtime to the actual users collection ID.
+ */
+export const DAILY_LOGS_COLLECTION: CollectionDefinition = {
+  name: "dailyLogs",
+  type: "base",
+  fields: [
+    {
+      name: "user",
+      type: "relation",
+      required: true,
+      collectionId: "users", // Will be resolved to actual ID at runtime
+      maxSelect: 1,
+      cascadeDelete: true,
+    },
+    {
+      name: "date",
+      type: "date",
+      required: true,
+    },
+    {
+      name: "cycleDay",
+      type: "number",
+      required: true,
+    },
+    {
+      name: "phase",
+      type: "text",
+      required: true,
+    },
+    {
+      name: "bodyBatteryCurrent",
+      type: "number",
+      required: false,
+    },
+    {
+      name: "bodyBatteryYesterdayLow",
+      type: "number",
+      required: false,
+    },
+    {
+      name: "hrvStatus",
+      type: "text",
+      required: false,
+    },
+    {
+      name: "weekIntensityMinutes",
+      type: "number",
+      required: false,
+    },
+    {
+      name: "phaseLimit",
+      type: "number",
+      required: false,
+    },
+    {
+      name: "remainingMinutes",
+      type: "number",
+      required: false,
+    },
+    {
+      name: "trainingDecision",
+      type: "text",
+      required: true,
+    },
+    {
+      name: "decisionReason",
+      type: "text",
+      required: true,
+    },
+    {
+      name: "notificationSentAt",
+      type: "date",
+      required: false,
+    },
+  ],
+};
+
+/**
+ * All collections that should exist in the database.
+ */
+const REQUIRED_COLLECTIONS = [PERIOD_LOGS_COLLECTION, DAILY_LOGS_COLLECTION];
+
+/**
+ * Gets the names of existing collections from PocketBase.
+ */
+export async function getExistingCollectionNames(
+  pb: PocketBase,
+): Promise<string[]> {
+  const collections = await pb.collections.getFullList();
+  return collections.map((c) => c.name);
+}
+
+/**
+ * Returns collection definitions that don't exist in the database.
+ */
+export function getMissingCollections(
+  existingNames: string[],
+): CollectionDefinition[] {
+  return REQUIRED_COLLECTIONS.filter(
+    (collection) => !existingNames.includes(collection.name),
+  );
+}
+
+/**
+ * Resolves collection name to actual collection ID.
+ */
+async function resolveCollectionId(
+  pb: PocketBase,
+  nameOrId: string,
+): Promise<string> {
+  const collection = await pb.collections.getOne(nameOrId);
+  return collection.id;
+}
+
+/**
+ * Creates a collection in PocketBase.
+ */
+async function createCollection(
+  pb: PocketBase,
+  collection: CollectionDefinition,
+): Promise<void> {
+  // Resolve any collection names to actual IDs for relation fields
+  const fields = await Promise.all(
+    collection.fields.map(async (field) => {
+      const baseField: Record<string, unknown> = {
+        name: field.name,
+        type: field.type,
+        required: field.required ?? false,
+      };
+
+      // For relation fields, resolve collectionId and add relation-specific props
+      if (field.type === "relation" && field.collectionId) {
+        const resolvedId = await resolveCollectionId(pb, field.collectionId);
+        baseField.collectionId = resolvedId;
+        baseField.maxSelect = field.maxSelect ?? 1;
+        baseField.cascadeDelete = field.cascadeDelete ?? false;
+      }
+
+      return baseField;
+    }),
+  );
+
+  await pb.collections.create({
+    name: collection.name,
+    type: collection.type,
+    fields,
+  });
+}
+
+/**
+ * Main setup function - creates missing collections.
+ */
+async function main(): Promise<void> {
+  // Validate environment
+  const pocketbaseUrl =
+    process.env.NEXT_PUBLIC_POCKETBASE_URL || "http://localhost:8090";
+  const adminEmail = process.env.POCKETBASE_ADMIN_EMAIL;
+  const adminPassword = process.env.POCKETBASE_ADMIN_PASSWORD;
+
+  if (!adminEmail || !adminPassword) {
+    console.error(
+      "Error: POCKETBASE_ADMIN_EMAIL and POCKETBASE_ADMIN_PASSWORD are required",
+    );
+    console.error("Usage:");
+    console.error(
+      "  POCKETBASE_ADMIN_EMAIL=admin@example.com POCKETBASE_ADMIN_PASSWORD=secret pnpm db:setup",
+    );
+    process.exit(1);
+  }
+
+  console.log(`Connecting to PocketBase at ${pocketbaseUrl}...`);
+
+  const pb = new PocketBase(pocketbaseUrl);
+  pb.autoCancellation(false);
+
+  // Authenticate as admin
+  try {
+    await pb
+      .collection("_superusers")
+      .authWithPassword(adminEmail, adminPassword);
+    console.log("Authenticated as admin");
+  } catch (error) {
+    console.error("Failed to authenticate as admin:", error);
+    process.exit(1);
+  }
+
+  // Get existing collections
+  const existingNames = await getExistingCollectionNames(pb);
+  console.log(
+    `Found ${existingNames.length} existing collections:`,
+    existingNames,
+  );
+
+  // Find and create missing collections
+  const missing = getMissingCollections(existingNames);
+
+  if (missing.length === 0) {
+    console.log("All required collections already exist. Nothing to do.");
+    return;
+  }
+
+  console.log(
+    `Creating ${missing.length} missing collection(s):`,
+    missing.map((c) => c.name),
+  );
+
+  for (const collection of missing) {
+    try {
+      await createCollection(pb, collection);
+      console.log(`  Created: ${collection.name}`);
+    } catch (error) {
+      console.error(`  Failed to create ${collection.name}:`, error);
+      process.exit(1);
+    }
+  }
+
+  console.log("Database setup complete!");
+}
+
+// Run main function when executed directly
+const isMainModule = typeof require !== "undefined" && require.main === module;
+
+// For ES modules / tsx execution
+if (isMainModule || process.argv[1]?.includes("setup-db")) {
+  main().catch((error) => {
+    console.error("Setup failed:", error);
+    process.exit(1);
+  });
+}
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index 72cc07d..f2a2730 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -32,7 +32,7 @@ export default function RootLayout({
       >
         <a
           href="#main-content"
-          className="sr-only focus:not-sr-only focus:absolute focus:top-4 focus:left-4 focus:z-50 focus:bg-white focus:px-4 focus:py-2 focus:rounded focus:shadow-lg focus:text-blue-600 focus:underline"
+          className="sr-only focus:not-sr-only focus:absolute focus:top-4 focus:left-4 focus:z-50 focus:bg-background focus:px-4 focus:py-2 focus:rounded focus:shadow-lg focus:text-blue-600 dark:focus:text-blue-400 focus:underline focus:border focus:border-input"
         >
           Skip to main content
         </a>
diff --git a/src/app/login/page.tsx b/src/app/login/page.tsx
index 7a715bc..e724814 100644
--- a/src/app/login/page.tsx
+++ b/src/app/login/page.tsx
@@ -200,7 +200,7 @@ export default function LoginPage() {
       >
         <div className="w-full max-w-md space-y-8 p-8">
           <h1 className="text-2xl font-bold text-center">PhaseFlow</h1>
-          <div className="text-center text-gray-500">Loading...</div>
+          <div className="text-center text-muted-foreground">Loading...</div>
         </div>
       </main>
     );
@@ -217,7 +217,7 @@ export default function LoginPage() {
         {error && (
           <div
             role="alert"
-            className="bg-red-50 border border-red-200 text-red-700 px-4 py-3 rounded"
+            className="bg-red-50 dark:bg-red-950 border border-red-200 dark:border-red-800 text-red-700 dark:text-red-400 px-4 py-3 rounded"
           >
             {error}
           </div>
@@ -241,7 +241,7 @@ export default function LoginPage() {
             <div>
               <label
                 htmlFor="email"
-                className="block text-sm font-medium text-gray-700"
+                className="block text-sm font-medium text-foreground"
               >
                 Email
               </label>
@@ -251,7 +251,7 @@ export default function LoginPage() {
                 value={email}
                 onChange={(e) => handleInputChange(setEmail, e.target.value)}
                 disabled={isLoading}
-                className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+                className="mt-1 block w-full rounded-md border border-input bg-background px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-muted disabled:cursor-not-allowed"
                 required
               />
             </div>
@@ -259,7 +259,7 @@ export default function LoginPage() {
             <div>
               <label
                 htmlFor="password"
-                className="block text-sm font-medium text-gray-700"
+                className="block text-sm font-medium text-foreground"
               >
                 Password
               </label>
@@ -269,7 +269,7 @@ export default function LoginPage() {
                 value={password}
                 onChange={(e) => handleInputChange(setPassword, e.target.value)}
                 disabled={isLoading}
-                className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+                className="mt-1 block w-full rounded-md border border-input bg-background px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-muted disabled:cursor-not-allowed"
                 required
               />
             </div>
diff --git a/src/app/settings/garmin/page.tsx b/src/app/settings/garmin/page.tsx
index dd581c1..0750707 100644
--- a/src/app/settings/garmin/page.tsx
+++ b/src/app/settings/garmin/page.tsx
@@ -156,7 +156,7 @@ export default function GarminSettingsPage() {
         <h1 className="text-2xl font-bold mb-8">
           Settings &gt; Garmin Connection
         </h1>
-        <p className="text-gray-500">Loading...</p>
+        <p className="text-muted-foreground">Loading...</p>
       </div>
     );
   }
@@ -176,28 +176,30 @@ export default function GarminSettingsPage() {
       {error && (
         <div
           role="alert"
-          className="bg-red-50 border border-red-200 text-red-700 px-4 py-3 rounded mb-6"
+          className="bg-red-50 dark:bg-red-950 border border-red-200 dark:border-red-800 text-red-700 dark:text-red-400 px-4 py-3 rounded mb-6"
         >
           {error}
         </div>
       )}
 
       {success && (
-        <div className="bg-green-50 border border-green-200 text-green-700 px-4 py-3 rounded mb-6">
+        <div className="bg-green-50 dark:bg-green-950 border border-green-200 dark:border-green-800 text-green-700 dark:text-green-400 px-4 py-3 rounded mb-6">
           {success}
         </div>
       )}
 
       <div className="max-w-lg space-y-6">
         {/* Connection Status Section */}
-        <div className="border border-gray-200 rounded-lg p-6">
+        <div className="border border-input rounded-lg p-6">
           <h2 className="text-lg font-semibold mb-4">Connection Status</h2>
 
           {status?.connected && !status.expired ? (
             <div className="space-y-4">
               <div className="flex items-center space-x-2">
                 <span className="w-3 h-3 bg-green-500 rounded-full" />
-                <span className="text-green-700 font-medium">Connected</span>
+                <span className="text-green-700 dark:text-green-400 font-medium">
+                  Connected
+                </span>
               </div>
 
               {status.warningLevel && (
@@ -205,8 +207,8 @@ export default function GarminSettingsPage() {
                   data-testid="expiry-warning"
                   className={`px-4 py-3 rounded ${
                     status.warningLevel === "critical"
-                      ? "bg-red-50 border border-red-200 text-red-700"
-                      : "bg-yellow-50 border border-yellow-200 text-yellow-700"
+                      ? "bg-red-50 dark:bg-red-950 border border-red-200 dark:border-red-800 text-red-700 dark:text-red-400"
+                      : "bg-yellow-50 dark:bg-yellow-950 border border-yellow-200 dark:border-yellow-800 text-yellow-700 dark:text-yellow-400"
                   }`}
                 >
                   {status.warningLevel === "critical"
@@ -215,7 +217,7 @@ export default function GarminSettingsPage() {
                 </div>
               )}
 
-              <p className="text-gray-600">
+              <p className="text-muted-foreground">
                 Token expires in{" "}
                 <span className="font-medium">
                   {status.daysUntilExpiry} days
@@ -235,33 +237,35 @@ export default function GarminSettingsPage() {
             <div className="space-y-4">
               <div className="flex items-center space-x-2">
                 <span className="w-3 h-3 bg-red-500 rounded-full" />
-                <span className="text-red-700 font-medium">Token Expired</span>
+                <span className="text-red-700 dark:text-red-400 font-medium">
+                  Token Expired
+                </span>
               </div>
-              <p className="text-gray-600">
+              <p className="text-muted-foreground">
                 Your Garmin tokens have expired. Please generate new tokens and
                 paste them below.
               </p>
             </div>
           ) : (
             <div className="flex items-center space-x-2">
-              <span className="w-3 h-3 bg-gray-400 rounded-full" />
-              <span className="text-gray-600">Not Connected</span>
+              <span className="w-3 h-3 bg-muted-foreground rounded-full" />
+              <span className="text-muted-foreground">Not Connected</span>
             </div>
           )}
         </div>
 
         {/* Token Input Section */}
         {showTokenInput && (
-          <div className="border border-gray-200 rounded-lg p-6">
+          <div className="border border-input rounded-lg p-6">
             <h2 className="text-lg font-semibold mb-4">Connect Garmin</h2>
 
             <div className="space-y-4">
-              <div className="bg-blue-50 border border-blue-200 text-blue-700 px-4 py-3 rounded text-sm">
+              <div className="bg-blue-50 dark:bg-blue-950 border border-blue-200 dark:border-blue-800 text-blue-700 dark:text-blue-400 px-4 py-3 rounded text-sm">
                 <p className="font-medium mb-2">Instructions:</p>
                 <ol className="list-decimal list-inside space-y-1">
                   <li>
                     Run{" "}
-                    <code className="bg-blue-100 px-1 rounded">
+                    <code className="bg-blue-100 dark:bg-blue-900 px-1 rounded">
                       python3 scripts/garmin_auth.py
                     </code>{" "}
                     locally
@@ -274,7 +278,7 @@ export default function GarminSettingsPage() {
               <div>
                 <label
                   htmlFor="tokenInput"
-                  className="block text-sm font-medium text-gray-700 mb-1"
+                  className="block text-sm font-medium text-foreground mb-1"
                 >
                   Paste Tokens (JSON)
                 </label>
@@ -285,7 +289,7 @@ export default function GarminSettingsPage() {
                   onChange={(e) => handleTokenChange(e.target.value)}
                   disabled={saving}
                   placeholder='{"oauth1": {...}, "oauth2": {...}, "expires_at": "..."}'
-                  className="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed font-mono text-sm"
+                  className="block w-full rounded-md border border-input bg-background px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-muted disabled:cursor-not-allowed font-mono text-sm"
                 />
               </div>
 
diff --git a/src/app/settings/page.tsx b/src/app/settings/page.tsx
index a18273e..1e9b802 100644
--- a/src/app/settings/page.tsx
+++ b/src/app/settings/page.tsx
@@ -132,7 +132,7 @@ export default function SettingsPage() {
     return (
       <main id="main-content" className="container mx-auto p-8">
         <h1 className="text-2xl font-bold mb-8">Settings</h1>
-        <p className="text-gray-500">Loading...</p>
+        <p className="text-muted-foreground">Loading...</p>
       </main>
     );
   }
@@ -152,31 +152,33 @@ export default function SettingsPage() {
       {error && (
         <div
           role="alert"
-          className="bg-red-50 border border-red-200 text-red-700 px-4 py-3 rounded mb-6"
+          className="bg-red-50 dark:bg-red-950 border border-red-200 dark:border-red-800 text-red-700 dark:text-red-400 px-4 py-3 rounded mb-6"
         >
           {error}
         </div>
       )}
 
       {success && (
-        <div className="bg-green-50 border border-green-200 text-green-700 px-4 py-3 rounded mb-6">
+        <div className="bg-green-50 dark:bg-green-950 border border-green-200 dark:border-green-800 text-green-700 dark:text-green-400 px-4 py-3 rounded mb-6">
           {success}
         </div>
       )}
 
       <div className="max-w-lg">
         <div className="mb-6">
-          <span className="block text-sm font-medium text-gray-700">Email</span>
-          <p className="mt-1 text-gray-900">{userData?.email}</p>
+          <span className="block text-sm font-medium text-foreground">
+            Email
+          </span>
+          <p className="mt-1 text-foreground">{userData?.email}</p>
         </div>
 
-        <div className="mb-6 p-4 border border-gray-200 rounded-lg">
+        <div className="mb-6 p-4 border border-input rounded-lg">
           <div className="flex items-center justify-between">
             <div>
-              <span className="block text-sm font-medium text-gray-700">
+              <span className="block text-sm font-medium text-foreground">
                 Garmin Connection
               </span>
-              <p className="mt-1 text-sm text-gray-500">
+              <p className="mt-1 text-sm text-muted-foreground">
                 {userData?.garminConnected
                   ? "Connected to Garmin"
                   : "Not connected"}
@@ -195,7 +197,7 @@ export default function SettingsPage() {
           <div>
             <label
               htmlFor="cycleLength"
-              className="block text-sm font-medium text-gray-700"
+              className="block text-sm font-medium text-foreground"
             >
               Cycle Length (days)
             </label>
@@ -209,10 +211,10 @@ export default function SettingsPage() {
                 handleInputChange(setCycleLength, Number(e.target.value))
               }
               disabled={saving}
-              className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+              className="mt-1 block w-full rounded-md border border-input bg-background px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-muted disabled:cursor-not-allowed"
               required
             />
-            <p className="mt-1 text-sm text-gray-500">
+            <p className="mt-1 text-sm text-muted-foreground">
               Typical range: 21-45 days
             </p>
           </div>
@@ -220,7 +222,7 @@ export default function SettingsPage() {
           <div>
             <label
               htmlFor="notificationTime"
-              className="block text-sm font-medium text-gray-700"
+              className="block text-sm font-medium text-foreground"
             >
               Notification Time
             </label>
@@ -232,10 +234,10 @@ export default function SettingsPage() {
                 handleInputChange(setNotificationTime, e.target.value)
               }
               disabled={saving}
-              className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+              className="mt-1 block w-full rounded-md border border-input bg-background px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-muted disabled:cursor-not-allowed [color-scheme:light] dark:[color-scheme:dark]"
               required
             />
-            <p className="mt-1 text-sm text-gray-500">
+            <p className="mt-1 text-sm text-muted-foreground">
               Time to receive daily email notification
             </p>
           </div>
@@ -243,7 +245,7 @@ export default function SettingsPage() {
           <div>
             <label
               htmlFor="timezone"
-              className="block text-sm font-medium text-gray-700"
+              className="block text-sm font-medium text-foreground"
             >
               Timezone
             </label>
@@ -253,11 +255,11 @@ export default function SettingsPage() {
               value={timezone}
               onChange={(e) => handleInputChange(setTimezone, e.target.value)}
               disabled={saving}
-              className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+              className="mt-1 block w-full rounded-md border border-input bg-background px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-muted disabled:cursor-not-allowed"
               placeholder="America/New_York"
               required
             />
-            <p className="mt-1 text-sm text-gray-500">
+            <p className="mt-1 text-sm text-muted-foreground">
               IANA timezone (e.g., America/New_York, Europe/London)
             </p>
           </div>
@@ -273,8 +275,8 @@ export default function SettingsPage() {
           </div>
         </form>
 
-        <div className="mt-8 pt-8 border-t border-gray-200">
-          <h2 className="text-lg font-medium text-gray-900 mb-4">Account</h2>
+        <div className="mt-8 pt-8 border-t border-input">
+          <h2 className="text-lg font-medium text-foreground mb-4">Account</h2>
           <button
             type="button"
             onClick={handleLogout}
diff --git a/src/components/dashboard/decision-card.tsx b/src/components/dashboard/decision-card.tsx
index 5e34512..5a26da7 100644
--- a/src/components/dashboard/decision-card.tsx
+++ b/src/components/dashboard/decision-card.tsx
@@ -12,21 +12,27 @@ function getStatusColors(status: Decision["status"]): {
 } {
   switch (status) {
     case "REST":
-      return { background: "bg-red-100 border-red-300", text: "text-red-700" };
+      return {
+        background:
+          "bg-red-100 dark:bg-red-900/50 border-red-300 dark:border-red-700",
+        text: "text-red-700 dark:text-red-300",
+      };
     case "GENTLE":
     case "LIGHT":
     case "REDUCED":
       return {
-        background: "bg-yellow-100 border-yellow-300",
-        text: "text-yellow-700",
+        background:
+          "bg-yellow-100 dark:bg-yellow-900/50 border-yellow-300 dark:border-yellow-700",
+        text: "text-yellow-700 dark:text-yellow-300",
       };
     case "TRAIN":
       return {
-        background: "bg-green-100 border-green-300",
-        text: "text-green-700",
+        background:
+          "bg-green-100 dark:bg-green-900/50 border-green-300 dark:border-green-700",
+        text: "text-green-700 dark:text-green-300",
       };
     default:
-      return { background: "border", text: "text-gray-600" };
+      return { background: "border", text: "text-muted-foreground" };
   }
 }
 
diff --git a/src/components/dashboard/mini-calendar.tsx b/src/components/dashboard/mini-calendar.tsx
index 9ece630..a9c0333 100644
--- a/src/components/dashboard/mini-calendar.tsx
+++ b/src/components/dashboard/mini-calendar.tsx
@@ -14,21 +14,24 @@ interface MiniCalendarProps {
 }
 
 const PHASE_COLORS: Record<CyclePhase, string> = {
-  MENSTRUAL: "bg-blue-100",
-  FOLLICULAR: "bg-green-100",
-  OVULATION: "bg-purple-100",
-  EARLY_LUTEAL: "bg-yellow-100",
-  LATE_LUTEAL: "bg-red-100",
+  MENSTRUAL: "bg-blue-100 dark:bg-blue-900/50 text-blue-900 dark:text-blue-100",
+  FOLLICULAR:
+    "bg-green-100 dark:bg-green-900/50 text-green-900 dark:text-green-100",
+  OVULATION:
+    "bg-purple-100 dark:bg-purple-900/50 text-purple-900 dark:text-purple-100",
+  EARLY_LUTEAL:
+    "bg-yellow-100 dark:bg-yellow-900/50 text-yellow-900 dark:text-yellow-100",
+  LATE_LUTEAL: "bg-red-100 dark:bg-red-900/50 text-red-900 dark:text-red-100",
 };
 
 const COMPACT_DAY_NAMES = ["S", "M", "T", "W", "T", "F", "S"];
 
 const PHASE_LEGEND = [
-  { name: "Menstrual", color: "bg-blue-100" },
-  { name: "Follicular", color: "bg-green-100" },
-  { name: "Ovulation", color: "bg-purple-100" },
-  { name: "Early Luteal", color: "bg-yellow-100" },
-  { name: "Late Luteal", color: "bg-red-100" },
+  { name: "Menstrual", color: "bg-blue-100 dark:bg-blue-900/50" },
+  { name: "Follicular", color: "bg-green-100 dark:bg-green-900/50" },
+  { name: "Ovulation", color: "bg-purple-100 dark:bg-purple-900/50" },
+  { name: "Early Luteal", color: "bg-yellow-100 dark:bg-yellow-900/50" },
+  { name: "Late Luteal", color: "bg-red-100 dark:bg-red-900/50" },
 ];
 
 function getDaysInMonth(year: number, month: number): number {
@@ -102,7 +105,7 @@ export function MiniCalendar({
         <button
           type="button"
           onClick={handlePreviousMonth}
-          className="p-1 hover:bg-gray-100 rounded text-sm"
+          className="p-1 hover:bg-muted rounded text-sm"
           aria-label="Previous month"
         >
           ←
@@ -117,7 +120,7 @@ export function MiniCalendar({
           <button
             type="button"
             onClick={handleTodayClick}
-            className="px-2 py-0.5 text-xs border rounded hover:bg-gray-100"
+            className="px-2 py-0.5 text-xs border rounded hover:bg-muted"
           >
             Today
           </button>
@@ -125,7 +128,7 @@ export function MiniCalendar({
         <button
           type="button"
           onClick={handleNextMonth}
-          className="p-1 hover:bg-gray-100 rounded text-sm"
+          className="p-1 hover:bg-muted rounded text-sm"
           aria-label="Next month"
         >
           →
@@ -138,7 +141,7 @@ export function MiniCalendar({
           <div
             // biome-ignore lint/suspicious/noArrayIndexKey: Day names are fixed and index is stable
             key={`day-header-${index}`}
-            className="text-center text-xs font-medium text-gray-500"
+            className="text-center text-xs font-medium text-muted-foreground"
           >
             {dayName}
           </div>
@@ -165,7 +168,7 @@ export function MiniCalendar({
               type="button"
               key={date.toISOString()}
               className={`p-1 text-xs rounded ${PHASE_COLORS[phase]} ${
-                isToday ? "ring-2 ring-black font-bold" : ""
+                isToday ? "ring-2 ring-foreground font-bold" : ""
               }`}
             >
               {date.getDate()}
@@ -182,7 +185,7 @@ export function MiniCalendar({
         {PHASE_LEGEND.map((phase) => (
           <div key={phase.name} className="flex items-center gap-0.5">
             <div className={`w-2 h-2 rounded ${phase.color}`} />
-            <span className="text-xs text-gray-600">{phase.name}</span>
+            <span className="text-xs text-muted-foreground">{phase.name}</span>
           </div>
         ))}
       </div>
diff --git a/vitest.config.ts b/vitest.config.ts
index 847dc82..f0dfc46 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -13,7 +13,7 @@ export default defineConfig({
   },
   test: {
     environment: "jsdom",
-    include: ["src/**/*.test.{ts,tsx}"],
+    include: ["src/**/*.test.{ts,tsx}", "scripts/**/*.test.ts"],
     setupFiles: ["./src/test-setup.ts"],
   },
 });