diff --git a/Overlord-Server/public/assets/nav.js b/Overlord-Server/public/assets/nav.js
index 9db86f5..2faaadc 100644
--- a/Overlord-Server/public/assets/nav.js
+++ b/Overlord-Server/public/assets/nav.js
@@ -5,6 +5,13 @@ import {
   subscribeStatus,
   subscribeUnread,
 } from "./notify-client.js";
+
+(function injectCustomCSS() {
+  const link = document.createElement("link");
+  link.rel = "stylesheet";
+  link.href = "/assets/custom.css";
+  document.head.appendChild(link);
+})();
 import { mountNav } from "./nav/template.js";
 import { createAdaptiveNavController } from "./nav/layout.js";
 import { applyUserRoleUI } from "./nav/role-ui.js";
diff --git a/Overlord-Server/public/assets/settings.js b/Overlord-Server/public/assets/settings.js
index e8025d6..0665993 100644
--- a/Overlord-Server/public/assets/settings.js
+++ b/Overlord-Server/public/assets/settings.js
@@ -56,6 +56,11 @@ const tlsCertbotCertFileInput = document.getElementById("tls-certbot-cert-file")
 const tlsCertbotKeyFileInput = document.getElementById("tls-certbot-key-file");
 const tlsCertbotCaFileInput = document.getElementById("tls-certbot-ca-file");
 
+const appearanceForm = document.getElementById("appearance-form");
+const appearancePermissionNote = document.getElementById("appearance-permission-note");
+const appearanceSaveBtn = document.getElementById("appearance-save-btn");
+const appearanceCustomCssInput = document.getElementById("appearance-custom-css");
+
 let currentUser = null;
 let securityConfig = null;
 let tlsConfig = null;
@@ -605,12 +610,68 @@ async function handleUnbanClick(event) {
   await loadBannedIps();
 }
 
+async function loadAppearanceSettings() {
+  if (!currentUser) return;
+
+  if (!isAdmin(currentUser.role)) {
+    if (appearancePermissionNote) appearancePermissionNote.classList.remove("hidden");
+    if (appearanceCustomCssInput) appearanceCustomCssInput.disabled = true;
+    if (appearanceSaveBtn) appearanceSaveBtn.disabled = true;
+    return;
+  }
+
+  if (appearancePermissionNote) appearancePermissionNote.classList.add("hidden");
+
+  try {
+    const res = await fetch("/api/settings/appearance", { credentials: "include" });
+    if (!res.ok) {
+      showMessage("Failed to load custom CSS settings.", "error");
+      return;
+    }
+    const data = await res.json().catch(() => ({}));
+    if (appearanceCustomCssInput) appearanceCustomCssInput.value = data.customCSS || "";
+    if (appearanceSaveBtn) appearanceSaveBtn.disabled = false;
+  } catch {
+    showMessage("Failed to load custom CSS settings.", "error");
+  }
+}
+
+async function saveAppearanceSettings(event) {
+  event.preventDefault();
+  if (!isAdmin(currentUser?.role)) {
+    showMessage("Admin role required.", "error");
+    return;
+  }
+
+  const customCSS = appearanceCustomCssInput ? appearanceCustomCssInput.value : "";
+  if (customCSS.length > 51200) {
+    showMessage("CSS exceeds the 50 KB size limit.", "error");
+    return;
+  }
+
+  const res = await fetch("/api/settings/appearance", {
+    method: "PUT",
+    headers: { "Content-Type": "application/json" },
+    credentials: "include",
+    body: JSON.stringify({ customCSS }),
+  });
+
+  const data = await res.json().catch(() => ({}));
+  if (!res.ok) {
+    showMessage(data.error || "Failed to save custom CSS.", "error");
+    return;
+  }
+
+  showMessage("Custom CSS saved. Reload the page to apply the new styles.");
+}
+
 async function init() {
   try {
     await loadCurrentUser();
     loadPrefs();
     await loadSecurityPolicy();
     await loadTlsSettings();
+    await loadAppearanceSettings();
     await loadBannedIps();
 
     passwordForm.addEventListener("submit", updatePassword);
@@ -618,6 +679,7 @@ async function init() {
     securityForm.addEventListener("submit", saveSecurityPolicy);
     tlsForm.addEventListener("submit", saveTlsSettings);
     tlsCertbotAutoBtn.addEventListener("click", runCertbotAutoSetup);
+    if (appearanceForm) appearanceForm.addEventListener("submit", saveAppearanceSettings);
     refreshBansBtn.addEventListener("click", loadBannedIps);
     bansTableBody.addEventListener("click", handleUnbanClick);
   } catch (error) {
diff --git a/Overlord-Server/public/login.html b/Overlord-Server/public/login.html
index bbc5c5e..e41bab8 100644
--- a/Overlord-Server/public/login.html
+++ b/Overlord-Server/public/login.html
@@ -18,6 +18,7 @@
       referrerpolicy="no-referrer"
     />
     <link rel="stylesheet" href="/assets/main.css" />
+    <link rel="stylesheet" href="/assets/custom.css" />
     <script
       src="https://cdnjs.cloudflare.com/ajax/libs/animejs/3.2.2/anime.min.js"
       crossorigin="anonymous"
diff --git a/Overlord-Server/public/settings.html b/Overlord-Server/public/settings.html
index 657750c..6c8df14 100644
--- a/Overlord-Server/public/settings.html
+++ b/Overlord-Server/public/settings.html
@@ -337,6 +337,37 @@
             </button>
           </form>
 
+          <form id="appearance-form" class="space-y-3 pt-1 border-t border-slate-800 pt-4">
+            <div>
+              <h3 class="font-medium">Custom CSS</h3>
+              <p class="text-xs text-slate-400">Admin-only. Paste custom CSS to override the default theme across all pages.</p>
+            </div>
+
+            <div id="appearance-permission-note" class="hidden rounded-lg border border-amber-800 bg-amber-900/20 text-amber-200 px-3 py-2 text-sm">
+              Only admins can update custom CSS.
+            </div>
+
+            <label class="block">
+              <span class="text-sm text-slate-300">Custom CSS</span>
+              <textarea
+                id="appearance-custom-css"
+                rows="12"
+                spellcheck="false"
+                placeholder="/* Paste your custom CSS here */&#10;:root { --color-primary: #f59e0b; }"
+                class="mt-1 w-full px-3 py-2 rounded-lg bg-slate-900 border border-slate-700 focus:outline-none focus:ring-2 focus:ring-sky-500 font-mono text-xs resize-y"
+              ></textarea>
+              <p class="text-xs text-slate-500 mt-1">Max 50 KB. Reload any open page after saving to see the new styles.</p>
+            </label>
+
+            <button
+              type="submit"
+              id="appearance-save-btn"
+              class="px-4 py-2 rounded-lg bg-violet-700 hover:bg-violet-600 transition-colors text-white font-medium"
+            >
+              <i class="fa-solid fa-paintbrush mr-2"></i>Save Custom CSS
+            </button>
+          </form>
+
           <p id="settings-message" class="hidden text-sm rounded-lg px-3 py-2"></p>
         </div>
 
diff --git a/Overlord-Server/src/config.ts b/Overlord-Server/src/config.ts
index 91b34c7..c8f7de0 100644
--- a/Overlord-Server/src/config.ts
+++ b/Overlord-Server/src/config.ts
@@ -55,6 +55,9 @@ export interface Config {
   enrollment: {
     requireApproval: boolean;
   };
+  appearance: {
+    customCSS: string;
+  };
 }
 
 const DEFAULT_CONFIG: Config = {
@@ -108,6 +111,9 @@ const DEFAULT_CONFIG: Config = {
   enrollment: {
     requireApproval: true,
   },
+  appearance: {
+    customCSS: "",
+  },
 };
 
 type SaveSecrets = {
@@ -423,6 +429,9 @@ export function loadConfig(): Config {
           ? String(process.env.OVERLORD_ENROLLMENT_REQUIRE_APPROVAL).toLowerCase() === "true"
           : (fileConfig.enrollment?.requireApproval ?? DEFAULT_CONFIG.enrollment.requireApproval),
     },
+    appearance: {
+      customCSS: fileConfig.appearance?.customCSS || DEFAULT_CONFIG.appearance.customCSS,
+    },
   };
 
   if (saveChanged) {
@@ -591,3 +600,18 @@ export async function updateTlsConfig(
   await writePersistentFileConfig(fileConfig);
   return next;
 }
+
+export async function updateAppearanceConfig(customCSS: string): Promise<Config["appearance"]> {
+  const current = getConfig();
+  const next = { customCSS: String(customCSS || "").slice(0, 51200) };
+
+  configCache = {
+    ...current,
+    appearance: next,
+  };
+
+  const fileConfig = readFileConfigForUpdate();
+  fileConfig.appearance = next;
+  await writePersistentFileConfig(fileConfig);
+  return next;
+}
diff --git a/Overlord-Server/src/server/routes/assets-routes.ts b/Overlord-Server/src/server/routes/assets-routes.ts
index 619f36b..fc76967 100644
--- a/Overlord-Server/src/server/routes/assets-routes.ts
+++ b/Overlord-Server/src/server/routes/assets-routes.ts
@@ -1,4 +1,5 @@
 import path from "path";
+import { getConfig } from "../../config";
 
 type AssetsRouteDeps = {
   PUBLIC_ROOT: string;
@@ -11,6 +12,16 @@ export async function handleAssetsRoutes(
   url: URL,
   deps: AssetsRouteDeps,
 ): Promise<Response | null> {
+  if (req.method === "GET" && url.pathname === "/assets/custom.css") {
+    const css = getConfig().appearance?.customCSS || "";
+    return new Response(css, {
+      headers: {
+        "Content-Type": "text/css; charset=utf-8",
+        "Cache-Control": "no-cache",
+      },
+    });
+  }
+
   if (req.method === "GET" && url.pathname === "/favicon.ico") {
     const file = Bun.file(path.join(deps.PUBLIC_ROOT, "assets", "favicon.ico"));
     if (await file.exists()) {
diff --git a/Overlord-Server/src/server/routes/misc-routes.ts b/Overlord-Server/src/server/routes/misc-routes.ts
index 99dbf76..4194298 100644
--- a/Overlord-Server/src/server/routes/misc-routes.ts
+++ b/Overlord-Server/src/server/routes/misc-routes.ts
@@ -1,6 +1,6 @@
 import { authenticateRequest } from "../../auth";
 import { AuditAction, getAuditLogs, logAudit } from "../../auditLog";
-import { getConfig, updateSecurityConfig, updateTlsConfig } from "../../config";
+import { getConfig, updateSecurityConfig, updateTlsConfig, updateAppearanceConfig } from "../../config";
 import { getClientMetricsSummary } from "../../db";
 import { metrics } from "../../metrics";
 import { requirePermission } from "../../rbac";
@@ -397,6 +397,50 @@ export async function handleMiscRoutes(
     );
   }
 
+  if (url.pathname === "/api/settings/appearance") {
+    const user = await authenticateRequest(req);
+    if (!user) {
+      return new Response("Unauthorized", { status: 401 });
+    }
+    if (user.role !== "admin") {
+      return new Response("Forbidden: Admin access required", { status: 403 });
+    }
+
+    if (req.method === "GET") {
+      return Response.json(
+        { customCSS: getConfig().appearance?.customCSS || "" },
+        { headers: deps.CORS_HEADERS },
+      );
+    }
+
+    if (req.method === "PUT") {
+      let body: any = {};
+      try {
+        body = await req.json();
+      } catch {
+        return Response.json({ error: "Invalid JSON" }, { status: 400 });
+      }
+
+      const customCSS = typeof body?.customCSS === "string" ? body.customCSS : "";
+      if (customCSS.length > 51200) {
+        return Response.json({ error: "CSS exceeds 50 KB limit" }, { status: 400 });
+      }
+
+      const updated = await updateAppearanceConfig(customCSS);
+
+      logAudit({
+        timestamp: Date.now(),
+        username: user.username,
+        ip: deps.requestIP?.(req)?.address || "unknown",
+        action: AuditAction.COMMAND,
+        details: "Updated custom CSS",
+        success: true,
+      });
+
+      return Response.json({ ok: true, customCSS: updated.customCSS }, { headers: deps.CORS_HEADERS });
+    }
+  }
+
   if (req.method === "GET" && url.pathname === "/api/cert/download" && deps.tlsCertPath) {
     try {
       const file = Bun.file(deps.tlsCertPath);