diff --git a/assets/css/shop/components.css b/assets/css/shop/components.css
index c8bd2d0..805447c 100644
--- a/assets/css/shop/components.css
+++ b/assets/css/shop/components.css
@@ -131,7 +131,7 @@
   /* ── Product prices (shared between cards and PDP) ── */
 
   .product-price--sale {
-    color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    color: var(--t-accent);
   }
 
   .product-price--compare {
@@ -254,7 +254,7 @@
   .hero-pre-title {
     font-family: var(--t-font-heading);
     font-weight: var(--t-heading-weight);
-    color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    color: var(--t-accent);
     font-size: var(--t-heading-display);
     margin-bottom: 1rem;
   }
@@ -398,7 +398,7 @@
   }
 
   .accent-link {
-    color: var(--t-accent-text, hsl(var(--t-accent-h) var(--t-accent-s) 38%));
+    color: var(--t-accent-text);
     text-decoration: none;
     cursor: pointer;
     font-size: var(--t-text-small);
@@ -457,7 +457,7 @@
   .collection-empty-link {
     display: inline-block;
     margin-top: 1rem;
-    color: var(--t-text-accent, hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l)));
+    color: var(--t-text-accent, var(--t-accent));
     text-decoration: underline;
   }
 
@@ -518,7 +518,7 @@
   }
 
   .pdp-thumbnail-active {
-    border: 2px solid hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    border: 2px solid var(--t-accent);
   }
 
   /* ── Variant selector ── */
@@ -556,8 +556,8 @@
     padding: 0;
 
     &[aria-pressed="true"] {
-      border-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
-      --tw-ring-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+      border-color: var(--t-accent);
+      --tw-ring-color: var(--t-accent);
     }
   }
 
@@ -572,8 +572,8 @@
     cursor: pointer;
 
     &[aria-pressed="true"] {
-      border-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
-      background: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l) / 0.1);
+      border-color: var(--t-accent);
+      background: color-mix(in oklch, var(--t-accent) 10%, transparent);
     }
   }
 
@@ -654,7 +654,7 @@
   }
 
   .atc-btn {
-    background-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    background-color: var(--t-accent);
     color: var(--t-text-inverse);
     border-radius: var(--t-radius-button);
     border: none;
@@ -762,7 +762,7 @@
   /* ── Announcement bar ── */
 
   .announcement-bar {
-    background-color: var(--t-accent-button, hsl(var(--t-accent-h) var(--t-accent-s) 42%));
+    background-color: var(--t-accent-button);
     color: var(--t-text-inverse);
     text-align: center;
     padding: 0.5rem 1rem;
@@ -867,7 +867,7 @@
     position: absolute;
     top: -4px;
     right: -4px;
-    background: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    background: var(--t-accent);
     color: var(--t-text-inverse);
     font-size: var(--t-text-caption);
     font-weight: 600;
@@ -889,7 +889,7 @@
 
     &[aria-current="page"] {
       color: var(--t-text-primary);
-      border-bottom-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+      border-bottom-color: var(--t-accent);
     }
   }
 
@@ -943,9 +943,9 @@
     }
 
     &[aria-current="page"] {
-      color: hsl(var(--t-accent-h) var(--t-accent-s) calc(var(--t-accent-l) - 15%));
+      color: color-mix(in oklch, var(--t-accent) 80%, black);
       font-weight: 600;
-      background-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l) / 0.1);
+      background-color: color-mix(in oklch, var(--t-accent) 10%, transparent);
 
       & svg {
         width: 1.5rem;
@@ -1273,7 +1273,7 @@
     padding: 0.75rem 1.5rem;
     font-weight: 600;
     transition: all 0.2s ease;
-    background: var(--t-accent-button, hsl(var(--t-accent-h) var(--t-accent-s) 42%));
+    background: var(--t-accent-button);
     color: var(--t-text-inverse);
     border-radius: var(--t-radius-button);
     border: none;
@@ -1692,7 +1692,7 @@
   /* ── Accent email link ── */
 
   .accent-email {
-    color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    color: var(--t-accent);
   }
 
   /* ── Card shared styles (info, tracking, newsletter, social cards) ── */
@@ -1767,7 +1767,7 @@
     align-items: center;
     gap: 0.5rem;
     margin-bottom: 0.5rem;
-    color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    color: var(--t-accent);
     text-decoration: none;
 
     & svg {
@@ -1879,7 +1879,7 @@
   .trust-badge-icon {
     flex-shrink: 0;
     margin-top: 0.125rem;
-    color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    color: var(--t-accent);
 
     & svg {
       width: 1.25rem;
diff --git a/assets/css/theme-layer2-attributes.css b/assets/css/theme-layer2-attributes.css
index bff30c7..396ca96 100644
--- a/assets/css/theme-layer2-attributes.css
+++ b/assets/css/theme-layer2-attributes.css
@@ -157,19 +157,21 @@
 
   /* Button Style Variants */
   &[data-button-style="outline"] {
-    & button[style*="background-color: hsl(var(--t-accent"],
-    & a[style*="background-color: hsl(var(--t-accent"] {
+    & .themed-button,
+    & .atc-btn,
+    & .cart-drawer-checkout {
       background-color: transparent !important;
-      color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l)) !important;
-      border: 2px solid hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l)) !important;
+      color: var(--t-accent) !important;
+      border: 2px solid var(--t-accent) !important;
     }
   }
 
   &[data-button-style="soft"] {
-    & button[style*="background-color: hsl(var(--t-accent"],
-    & a[style*="background-color: hsl(var(--t-accent"] {
-      background-color: hsl(var(--t-accent-h) var(--t-accent-s) 90%) !important;
-      color: hsl(var(--t-accent-h) var(--t-accent-s) 30%) !important;
+    & .themed-button,
+    & .atc-btn,
+    & .cart-drawer-checkout {
+      background-color: color-mix(in oklch, var(--t-accent) 12%, var(--t-surface-base)) !important;
+      color: color-mix(in oklch, var(--t-accent) 80%, black) !important;
       border: 2px solid transparent !important;
     }
   }
@@ -231,12 +233,12 @@
   }
 
   & .filter-pill-active {
-    background-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    background-color: var(--t-accent);
     color: var(--t-text-inverse);
     border-color: transparent;
 
     &:hover {
-      background-color: hsl(var(--t-accent-h) var(--t-accent-s) calc(var(--t-accent-l) - 5%));
+      background-color: var(--t-accent-hover);
       color: var(--t-text-inverse);
     }
   }
@@ -250,7 +252,7 @@
 
     &:focus {
       outline: none;
-      border-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+      border-color: var(--t-accent);
     }
 
     &::placeholder {
@@ -269,12 +271,12 @@
 
     &:focus {
       outline: none;
-      border-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+      border-color: var(--t-accent);
     }
   }
 
   & .themed-button {
-    background-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    background-color: var(--t-accent);
     color: var(--t-text-inverse);
     border-radius: var(--t-radius-button);
     border: none;
@@ -322,7 +324,7 @@
 }
 
 .badge-new {
-  background-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+  background-color: var(--t-accent);
   color: var(--t-text-inverse);
 }
 
diff --git a/assets/css/theme-semantic.css b/assets/css/theme-semantic.css
index 124a17a..a50c751 100644
--- a/assets/css/theme-semantic.css
+++ b/assets/css/theme-semantic.css
@@ -13,21 +13,19 @@
   color: var(--t-text-primary);
   font-family: var(--t-font-body);
 
-  /* Accent color - HSL components set dynamically by CSS generator */
-  --t-accent-h: 24;
-  --t-accent-s: 95%;
-  --t-accent-l: 53%;
+  /* Accent colour — oklch components set dynamically by CSSGenerator */
+  --t-accent-l: 65%;
+  --t-accent-c: 0.2;
+  --t-accent-h: 47;
 
-  --t-accent: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
-  --t-accent-hover: hsl(var(--t-accent-h) var(--t-accent-s) calc(var(--t-accent-l) - 8%));
-  --t-accent-subtle: hsl(var(--t-accent-h) 40% 95%);
-  --t-accent-ring: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l) / 0.4);
+  --t-accent: oklch(var(--t-accent-l) var(--t-accent-c) var(--t-accent-h));
+  --t-accent-hover: color-mix(in oklch, var(--t-accent) 85%, black);
+  --t-accent-subtle: color-mix(in oklch, var(--t-accent) 8%, var(--t-surface-base));
+  --t-accent-ring: oklch(var(--t-accent-l) var(--t-accent-c) var(--t-accent-h) / 0.4);
 
   /* WCAG AA compliant accent variants for better contrast */
-  /* Darker accent for text on light backgrounds (4.5:1 with white) */
-  --t-accent-text: hsl(var(--t-accent-h) var(--t-accent-s) 38%);
-  /* Darker accent for button backgrounds to ensure 4.5:1 with white text */
-  --t-accent-button: hsl(var(--t-accent-h) var(--t-accent-s) 42%);
+  --t-accent-text: color-mix(in oklch, var(--t-accent) 80%, black);
+  --t-accent-button: color-mix(in oklch, var(--t-accent) 85%, black);
 
   /* Secondary colors */
   --t-secondary-accent: #ea580c;
@@ -117,7 +115,7 @@
 
   /* Dark mode accent-subtle override */
   &[data-mood="dark"] {
-    --t-accent-subtle: hsl(var(--t-accent-h) 30% 15%);
+    --t-accent-subtle: color-mix(in oklch, var(--t-accent) 15%, black);
   }
 }
 
@@ -137,7 +135,7 @@
   & textarea:focus-visible,
   & [tabindex]:focus-visible,
   & details summary:focus-visible {
-    outline: 2px solid hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+    outline: 2px solid var(--t-accent);
     outline-offset: 2px;
   }
 
@@ -230,9 +228,9 @@
   }
 
   &.active {
-    background-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l) / 0.12);
-    color: hsl(var(--t-accent-h) var(--t-accent-s) calc(var(--t-accent-l) - 15%));
-    border-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l) / 0.25);
+    background-color: color-mix(in oklch, var(--t-accent) 12%, transparent);
+    color: color-mix(in oklch, var(--t-accent) 80%, black);
+    border-color: color-mix(in oklch, var(--t-accent) 25%, transparent);
     font-weight: 600;
   }
 }
@@ -273,7 +271,7 @@
   top: -100px;
   left: 50%;
   transform: translateX(-50%);
-  background: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+  background: var(--t-accent);
   color: var(--t-text-inverse);
   padding: 0.75rem 1.5rem;
   z-index: 9999;
@@ -312,5 +310,5 @@
 
 /* Active nav underline — must stay unlayered to match the base border above */
 .shop-nav [aria-current="page"] {
-  border-bottom-color: hsl(var(--t-accent-h) var(--t-accent-s) var(--t-accent-l));
+  border-bottom-color: var(--t-accent);
 }
diff --git a/lib/berrypod/theme/css_generator.ex b/lib/berrypod/theme/css_generator.ex
index 158b670..93d80d6 100644
--- a/lib/berrypod/theme/css_generator.ex
+++ b/lib/berrypod/theme/css_generator.ex
@@ -61,7 +61,8 @@ defmodule Berrypod.Theme.CSSGenerator do
   # Mood colors - surface, text, and border colors
   defp generate_mood("neutral") do
     """
-    --t-surface-base: #ffffff;
+    color-scheme: light;
+      --t-surface-base: #ffffff;
       --t-surface-raised: #ffffff;
       --t-surface-sunken: #f5f5f5;
       --t-surface-overlay: rgba(255, 255, 255, 0.95);
@@ -76,7 +77,8 @@ defmodule Berrypod.Theme.CSSGenerator do
 
   defp generate_mood("warm") do
     """
-    --t-surface-base: #fdf8f3;
+    color-scheme: light;
+      --t-surface-base: #fdf8f3;
       --t-surface-raised: #fffcf8;
       --t-surface-sunken: #f5ebe0;
       --t-surface-overlay: rgba(253, 248, 243, 0.95);
@@ -91,7 +93,8 @@ defmodule Berrypod.Theme.CSSGenerator do
 
   defp generate_mood("cool") do
     """
-    --t-surface-base: #f4f7fb;
+    color-scheme: light;
+      --t-surface-base: #f4f7fb;
       --t-surface-raised: #f8fafc;
       --t-surface-sunken: #e8eff7;
       --t-surface-overlay: rgba(244, 247, 251, 0.95);
@@ -106,7 +109,8 @@ defmodule Berrypod.Theme.CSSGenerator do
 
   defp generate_mood("dark") do
     """
-    --t-surface-base: #0a0a0a;
+    color-scheme: dark;
+      --t-surface-base: #0a0a0a;
       --t-surface-raised: #171717;
       --t-surface-sunken: #000000;
       --t-surface-overlay: rgba(23, 23, 23, 0.95);
@@ -239,14 +243,14 @@ defmodule Berrypod.Theme.CSSGenerator do
   # Fallback for any other density value
   defp generate_density(_), do: generate_density("balanced")
 
-  # Accent color with HSL breakdown
+  # Accent color with oklch breakdown
   defp generate_accent(hex_color) do
-    {h, s, l} = hex_to_hsl(hex_color)
+    {l, c, h} = hex_to_oklch(hex_color)
 
     """
-      --t-accent-h: #{h};
-      --t-accent-s: #{s}%;
       --t-accent-l: #{l}%;
+      --t-accent-c: #{c};
+      --t-accent-h: #{h};
     """
   end
 
@@ -334,46 +338,55 @@ defmodule Berrypod.Theme.CSSGenerator do
     "--t-image-aspect-ratio: 4 / 3;"
   end
 
-  # Convert hex color to HSL
-  defp hex_to_hsl("#" <> hex), do: hex_to_hsl(hex)
+  # Convert hex colour to oklch (lightness%, chroma, hue°)
+  # Pipeline: hex → sRGB → linear RGB → XYZ (D65) → oklab → oklch
+  defp hex_to_oklch("#" <> hex), do: hex_to_oklch(hex)
 
-  defp hex_to_hsl(hex) when byte_size(hex) == 6 do
+  defp hex_to_oklch(hex) when byte_size(hex) == 6 do
     {r, ""} = Integer.parse(String.slice(hex, 0..1), 16)
     {g, ""} = Integer.parse(String.slice(hex, 2..3), 16)
     {b, ""} = Integer.parse(String.slice(hex, 4..5), 16)
 
-    # Normalize RGB values to 0-1
-    r = r / 255
-    g = g / 255
-    b = b / 255
+    # sRGB to linear RGB (inverse gamma)
+    lr = srgb_to_linear(r / 255)
+    lg = srgb_to_linear(g / 255)
+    lb = srgb_to_linear(b / 255)
 
-    max = Enum.max([r, g, b])
-    min = Enum.min([r, g, b])
-    delta = max - min
+    # Linear RGB to oklab via the Björn Ottosson method
+    # First: linear sRGB → LMS (cube root of cone response)
+    l_ = :math.pow(0.4122214708 * lr + 0.5363325363 * lg + 0.0514459929 * lb, 1 / 3)
+    m_ = :math.pow(0.2119034982 * lr + 0.6806995451 * lg + 0.1073969566 * lb, 1 / 3)
+    s_ = :math.pow(0.0883024619 * lr + 0.2817188376 * lg + 0.6299787005 * lb, 1 / 3)
 
-    # Calculate lightness
-    l = (max + min) / 2
+    # LMS to oklab
+    ok_l = 0.2104542553 * l_ + 0.7936177850 * m_ - 0.0040720468 * s_
+    ok_a = 1.9779984951 * l_ - 2.4285922050 * m_ + 0.4505937099 * s_
+    ok_b = 0.0259040371 * l_ + 0.7827717662 * m_ - 0.8086757660 * s_
 
-    # Calculate saturation and hue
-    {h, s} =
-      if delta == 0 do
-        {0, 0}
+    # oklab to oklch
+    c = :math.sqrt(ok_a * ok_a + ok_b * ok_b)
+
+    h =
+      if c < 0.0001 do
+        0.0
       else
-        s = if l > 0.5, do: delta / (2 - max - min), else: delta / (max + min)
-
-        h =
-          cond do
-            max == r -> (g - b) / delta + if(g < b, do: 6, else: 0)
-            max == g -> (b - r) / delta + 2
-            max == b -> (r - g) / delta + 4
-          end
-
-        {h * 60, s}
+        h_rad = :math.atan2(ok_b, ok_a)
+        h_deg = h_rad * 180 / :math.pi()
+        if h_deg < 0, do: h_deg + 360, else: h_deg
       end
 
-    {round(h), round(s * 100), round(l * 100)}
+    # Return as {lightness%, chroma, hue°} rounded for CSS
+    {
+      Float.round(ok_l * 100, 2),
+      Float.round(c, 4),
+      Float.round(h, 2)
+    }
   end
 
-  # Handle invalid hex values
-  defp hex_to_hsl(_), do: {0, 0, 50}
+  # Handle invalid hex values (neutral grey fallback)
+  defp hex_to_oklch(_), do: {50.0, 0.0, 0.0}
+
+  # sRGB gamma decompression (IEC 61966-2-1)
+  defp srgb_to_linear(v) when v <= 0.04045, do: v / 12.92
+  defp srgb_to_linear(v), do: :math.pow((v + 0.055) / 1.055, 2.4)
 end
diff --git a/lib/berrypod_web/admin_layout_hook.ex b/lib/berrypod_web/admin_layout_hook.ex
index 20cf44e..f8e0a24 100644
--- a/lib/berrypod_web/admin_layout_hook.ex
+++ b/lib/berrypod_web/admin_layout_hook.ex
@@ -1,21 +1,40 @@
 defmodule BerrypodWeb.AdminLayoutHook do
   @moduledoc """
-  LiveView on_mount hook that assigns the current path for admin sidebar navigation.
+  LiveView on_mount hook that assigns the current path for admin sidebar navigation
+  and loads theme settings for the admin layout.
   """
   import Phoenix.Component
 
+  alias Berrypod.Settings
+  alias Berrypod.Theme.{CSSCache, CSSGenerator}
+
   def on_mount(:assign_current_path, _params, _session, socket) do
+    theme_settings = Settings.get_theme_settings()
+
+    generated_css =
+      case CSSCache.get() do
+        {:ok, css} ->
+          css
+
+        :miss ->
+          css = CSSGenerator.generate(theme_settings, &BerrypodWeb.Endpoint.static_path/1)
+          CSSCache.put(css)
+          css
+      end
+
     socket =
       socket
       |> assign(:current_path, "")
-      |> assign(:site_live, Berrypod.Settings.site_live?())
+      |> assign(:site_live, Settings.site_live?())
+      |> assign(:theme_settings, theme_settings)
+      |> assign(:generated_css, generated_css)
       |> Phoenix.LiveView.attach_hook(:set_current_path, :handle_params, fn _params,
                                                                             uri,
                                                                             socket ->
         {:cont,
          socket
          |> assign(:current_path, URI.parse(uri).path)
-         |> assign(:site_live, Berrypod.Settings.site_live?())}
+         |> assign(:site_live, Settings.site_live?())}
       end)
 
     {:cont, socket}
diff --git a/lib/berrypod_web/components/layouts/admin_root.html.heex b/lib/berrypod_web/components/layouts/admin_root.html.heex
index 78a5c8b..8ddce52 100644
--- a/lib/berrypod_web/components/layouts/admin_root.html.heex
+++ b/lib/berrypod_web/components/layouts/admin_root.html.heex
@@ -7,12 +7,23 @@
     <.live_title default="Admin" suffix=" · Berrypod">
       {assigns[:page_title]}
     </.live_title>
+    <!-- Preload critical fonts for the current typography preset -->
+    <%= for preload <- Berrypod.Theme.Fonts.preload_links(
+          @theme_settings.typography,
+          &BerrypodWeb.Endpoint.static_path/1
+        ) do %>
+      <link rel="preload" href={preload.href} as="font" type="font/woff2" crossorigin />
+    <% end %>
     <!-- Pre-declare layer order so shop reset < Tailwind base regardless of load order -->
     <style>
       @layer properties, reset, primitives, tokens, theme, base, components, layout, utilities, overrides;
     </style>
     <link phx-track-static rel="stylesheet" href={~p"/assets/css/admin.css"} />
     <link phx-track-static rel="stylesheet" href={~p"/assets/css/shop.css"} />
+    <!-- Generated theme CSS with @font-face declarations -->
+    <style id="theme-css">
+      <%= Phoenix.HTML.raw(@generated_css) %>
+    </style>
     <script defer phx-track-static src={~p"/assets/js/app.js"}>
     </script>
     <script>
diff --git a/lib/berrypod_web/router.ex b/lib/berrypod_web/router.ex
index 7f5277f..525348e 100644
--- a/lib/berrypod_web/router.ex
+++ b/lib/berrypod_web/router.ex
@@ -40,6 +40,7 @@ defmodule BerrypodWeb.Router do
 
   pipeline :admin do
     plug :put_root_layout, html: {BerrypodWeb.Layouts, :admin_root}
+    plug BerrypodWeb.Plugs.LoadTheme
   end
 
   # Public storefront (root level)
diff --git a/test/berrypod/settings_test.exs b/test/berrypod/settings_test.exs
index 8a0f30c..ee39607 100644
--- a/test/berrypod/settings_test.exs
+++ b/test/berrypod/settings_test.exs
@@ -76,15 +76,15 @@ defmodule Berrypod.SettingsTest do
       # Cache should now contain new CSS with the red accent color
       {:ok, updated_css} = CSSCache.get()
       assert updated_css =~ ".themed {"
-      # Red = hue 0
-      assert updated_css =~ "--t-accent-h: 0"
+      # Red in oklch ≈ hue 29°
+      assert updated_css =~ "--t-accent-h: 29.23"
 
       # Change to blue
       {:ok, _settings} = Settings.update_theme_settings(%{accent_color: "#0000ff"})
 
       {:ok, blue_css} = CSSCache.get()
-      # Blue = hue 240
-      assert blue_css =~ "--t-accent-h: 240"
+      # Blue in oklch ≈ hue 264°
+      assert blue_css =~ "--t-accent-h: 264.05"
 
       # Restore default
       CSSCache.warm()
diff --git a/test/berrypod/theme/css_generator_test.exs b/test/berrypod/theme/css_generator_test.exs
index d43f0fc..fcbd725 100644
--- a/test/berrypod/theme/css_generator_test.exs
+++ b/test/berrypod/theme/css_generator_test.exs
@@ -12,44 +12,54 @@ defmodule Berrypod.Theme.CSSGeneratorTest do
       assert is_binary(css)
       # CSS targets .themed (used by both shop and preview)
       assert css =~ ".themed {"
-      assert css =~ "--t-accent-h:"
-      assert css =~ "--t-accent-s:"
       assert css =~ "--t-accent-l:"
+      assert css =~ "--t-accent-c:"
+      assert css =~ "--t-accent-h:"
       # Should include all theme token categories
       assert css =~ "--t-surface-base:"
       assert css =~ "--t-font-heading:"
       assert css =~ "--t-radius-sm:"
       assert css =~ "--t-density:"
+      # Should include color-scheme
+      assert css =~ "color-scheme:"
     end
 
-    test "converts hex colors to HSL" do
+    test "converts hex colours to oklch" do
       settings = %ThemeSettings{accent_color: "#ff0000"}
       css = CSSGenerator.generate(settings)
 
-      # Red should be H=0, S=100%, L=50%
-      assert css =~ "--t-accent-h: 0"
-      assert css =~ "--t-accent-s: 100%"
-      assert css =~ "--t-accent-l: 50%"
+      # Red in oklch: L≈62.8%, C≈0.2577, H≈29.23°
+      assert css =~ "--t-accent-l: 62.8"
+      assert css =~ "--t-accent-c: 0.257"
+      assert css =~ "--t-accent-h: 29.2"
     end
 
-    test "handles blue accent color" do
+    test "handles blue accent colour" do
       settings = %ThemeSettings{accent_color: "#0000ff"}
       css = CSSGenerator.generate(settings)
 
-      # Blue should be H=240, S=100%, L=50%
-      assert css =~ "--t-accent-h: 240"
-      assert css =~ "--t-accent-s: 100%"
-      assert css =~ "--t-accent-l: 50%"
+      # Blue in oklch: L≈45.2%, C≈0.3132, H≈264.05°
+      assert css =~ "--t-accent-l: 45.2"
+      assert css =~ "--t-accent-c: 0.313"
+      assert css =~ "--t-accent-h: 264."
     end
 
-    test "handles green accent color" do
+    test "handles green accent colour" do
       settings = %ThemeSettings{accent_color: "#00ff00"}
       css = CSSGenerator.generate(settings)
 
-      # Green should be H=120, S=100%, L=50%
-      assert css =~ "--t-accent-h: 120"
-      assert css =~ "--t-accent-s: 100%"
-      assert css =~ "--t-accent-l: 50%"
+      # Green in oklch: L≈86.6%, C≈0.2948, H≈142.5°
+      assert css =~ "--t-accent-l: 86.6"
+      assert css =~ "--t-accent-c: 0.294"
+      assert css =~ "--t-accent-h: 142."
+    end
+
+    test "sets color-scheme based on mood" do
+      light = CSSGenerator.generate(%ThemeSettings{mood: "neutral"})
+      dark = CSSGenerator.generate(%ThemeSettings{mood: "dark"})
+
+      assert light =~ "color-scheme: light"
+      assert dark =~ "color-scheme: dark"
     end
 
     test "includes secondary colors" do
diff --git a/test/berrypod_web/live/theme_css_consistency_test.exs b/test/berrypod_web/live/theme_css_consistency_test.exs
index 4f23ad9..6df57f5 100644
--- a/test/berrypod_web/live/theme_css_consistency_test.exs
+++ b/test/berrypod_web/live/theme_css_consistency_test.exs
@@ -145,9 +145,9 @@ defmodule BerrypodWeb.ThemeCSSConsistencyTest do
       assert css =~ "--space-lg:"
 
       # Slider-controlled values
-      assert css =~ "--t-accent-h:"
-      assert css =~ "--t-accent-s:"
       assert css =~ "--t-accent-l:"
+      assert css =~ "--t-accent-c:"
+      assert css =~ "--t-accent-h:"
       assert css =~ "--t-font-size-scale:"
       assert css =~ "--t-heading-weight-override:"
     end