diff --git a/src/assets/stylesheets/DesignSystemButton.scss b/src/assets/stylesheets/DesignSystemButton.scss
index c66fe1f08..b980bb875 100644
--- a/src/assets/stylesheets/DesignSystemButton.scss
+++ b/src/assets/stylesheets/DesignSystemButton.scss
@@ -113,11 +113,7 @@
 
 .--light * {
   .rpf-button--secondary {
-    span {
-      color: $rpf-text-primary;
-    }
-
-    &::before {
+     &::before {
       background-color: rgba($rpf-white, 1);
     }
 
diff --git a/src/assets/stylesheets/InternalStyles.scss b/src/assets/stylesheets/InternalStyles.scss
index 923d89be9..bc09b8220 100644
--- a/src/assets/stylesheets/InternalStyles.scss
+++ b/src/assets/stylesheets/InternalStyles.scss
@@ -43,6 +43,8 @@
 
 @use "./settings/fonts" as fonts;
 
+// Default styles
+
 :host {
   font-size: 1.6rem;
 }
@@ -100,10 +102,10 @@ svg {
 }
 
 button:focus-visible {
-  outline: 2px solid $rpf-black;
+  outline: 2px solid var(--rpf-black);
 }
 
-//override for a pesky teal icon
+//override for a pesky navy icon
 .select-buttons__tick--selected {
   svg {
     path {
@@ -113,33 +115,125 @@ button:focus-visible {
 }
 
 .--light {
-  --editor-color-layer-1: #{$rpf-teal-100};
-  --editor-color-layer-2: #{$rpf-white};
-  --editor-color-layer-3: #{$rpf-white};
-  --editor-color-outline: #{$rpf-grey-150};
-  //theme change to match WC navy colors
-  --editor-color-theme: #{$rpf-navy-800};
-  --editor-color-theme-secondary: #{$rpf-teal-900};
-  --editor-color-theme-tertiary: #{$rpf-teal-100};
-  --editor-color-text: #{$rpf-text-primary};
-  --editor-color-text-secondary: #{$rpf-text-secondary};
-  --editor-color-tab-background: #{$rpf-off-white};
+  // Theme colours
+  --editor-color-layer-1: var(--rpf-teal-100);
+  --editor-color-layer-2: var(--rpf-white);
+  --editor-color-layer-3: var(--rpf-white);
+  --editor-color-outline: var(--rpf-grey-150);
+  --editor-color-theme: var(--rpf-navy-800);
+  --editor-color-theme-secondary: var(--rpf-navy-900);
+  --editor-color-theme-tertiary: var(--rpf-navy-100);
+  --editor-color-text: var(--rpf-text-primary);
+  --editor-color-text-secondary: var(--rpf-text-secondary);
+  --editor-color-tab-background: var(--rpf-off-white);
+
+  --rpf-files-list-item-active: var(--rpf-navy-secondary-tertiary-active);
+  --rpf-files-list-item-hover: var(--rpf-navy-secondary-tertiary-hover);
+  --rpf-tab-button-hover: var(--rpf-grey-100);
+  --rpf-tab-button-background: inherit;
+  --rpf-tab-border-bottom-selected: var(--editor-color-theme-secondary);
+
+  // Sidebar
+  --sidebar-border: var(--editor-color-outline);
+  --sidebar-background: var(--rpf-white);
+  --sidebar-background-selected: var(--rpf-off-white);
+  --sidebar-panel-background: var(--rpf-white);
+  --sidebar-option-hover: var(--rpf-grey-100);
+  --sidebar-option-selected-icon: var(--rpf-black);
+  --sidebar-option-selected-border: var(--editor-color-theme-secondary);
+  --sidebar-option-selected-background: var(--editor-color-theme-tertiary);
+  --sidebar-option-selected-background-hover: var(--rpf-navy-200);
+
+  .btn,
+  .rpf-button {
+    // Primary button
+    --rpf-button-primary-background-color: var(--editor-color-theme);
+    --rpf-button-primary-background-color-focus: var(--editor-color-theme);
+    --rpf-button-primary-background-color-hover: var(--editor-color-theme-secondary);
+    --rpf-button-primary-background-color-active: var(--rpf-navy-600);
+    --rpf-button-primary-background-color-disabled: var(--rpf-navy-200);
+    --rpf-button-primary-color-disabled: var(--rpf-grey-600);
+    --rpf-button-primary-text-color: var(--rpf-white);
+
+    // Secondary button
+    --rpf-button-secondary-background-color: var(--editor-color-theme);
+    --rpf-button-secondary-background-color-focus: var(--rpf-brand-raspberry);
+    --rpf-button-secondary-background-color-hover: var(--editor-color-theme-tertiary);
+    --rpf-button-secondary-border-color: var(--editor-color-theme);
+    --rpf-button-secondary-border-color-hover: var(--editor-color-theme-secondary);
+    --rpf-button-secondary-background-color-active: var(--editor-color-theme-secondary);
+    --rpf-button-secondary-background-color-disabled: var(--rpf-grey-50);
+    --rpf-button-secondary-text-color: var(--editor-color-theme);
+
+    // Tertiary button
+    --rpf-button-tertiary-text-color-hover: var(--rpf-grey-600);
+    --rpf-button-tertiary-danger-text-color: var(--rpf-alert-error);
+    --rpf-button-tertiary-danger-background-color-hover: rgba(0, 0, 0, 0.03);
+    --rpf-button-tertiary-danger-background-color-active: rgba(0, 0, 0, 0.05);
+  }
 }
 
 .--dark {
-  --editor-color-layer-1: #{$rpf-grey-850};
-  --editor-color-layer-2: #{$rpf-white};
-  --editor-color-layer-3: #{$rpf-grey-700};
-  --editor-color-outline: #{$rpf-grey-600};
-  --editor-color-theme: #{$rpf-navy-800};
-  --editor-color-theme-secondary: #{$rpf-teal-400};
-  --editor-color-theme-tertiary: #{$rpf-teal-900};
-  --editor-color-text: #{$rpf-white};
-  --editor-color-text-secondary: #{$rpf-text-secondary-darkmode};
-  --rpf-button-secondary-text-color: #{$rpf-white};
-  --editor-color-tab-background: #{$rpf-grey-700};
-
-  .rpf-button--secondary {
-    border-color: $rpf-navy-800;
+  // Theme colours
+  --editor-color-layer-1: var(--rpf-grey-850);
+  --editor-color-layer-2: var(--rpf-grey-800);
+  --editor-color-layer-3: var(--rpf-grey-700);
+  --editor-color-outline: var(--rpf-grey-600);
+  --editor-color-theme: var(--rpf-navy-400);
+  --editor-color-theme-secondary: var(--rpf-navy-400);
+  --editor-color-theme-tertiary: var(--rpf-navy-900);
+  --editor-color-text: var(--rpf-white);
+  --editor-color-text-secondary: var(--rpf-text-secondary-darkmode);
+
+  --rpf-files-list-item-active: var(--rpf-grey-secondary-tertiary-active);
+  --rpf-files-list-item-hover: var(--rpf-grey-secondary-tertiary-hover);
+  --rpf-tab-button-hover: var(--rpf-grey-900);
+  --rpf-tab-button-background: var(--editor-color-layer-2);
+  --rpf-tab-border-bottom-selected: var(--editor-color-theme);
+
+  // Sidebar
+  --sidebar-border: var(--editor-color-outline);
+  --sidebar-background: var(--editor-color-layer-2);
+  --sidebar-background-selected: var(--editor-color-layer-2);
+  --sidebar-panel-background: var(--editor-color-layer-3);
+  --sidebar-option-hover: var(--editor-color-outline);
+  --sidebar-option-selected-icon: var(--rpf-white);
+  --sidebar-option-selected-border: var(--editor-color-theme);
+  --sidebar-option-selected-background: var(--editor-color-theme-tertiary);
+  --sidebar-option-selected-background-hover: var(--rpf-navy-800);
+
+  --editor-color-tab-background: var(--editor-color-layer-3);
+
+  // Buttons
+  .btn,
+  .rpf-button {
+    // Primary button
+    --rpf-button-primary-text-color: var(--rpf-black);
+    --rpf-button-primary-background-color: var(--editor-color-theme);
+    --rpf-button-primary-background-color-focus: var(--editor-color-theme);
+    --rpf-button-primary-background-color-active: var(--rpf-navy-200);
+    --rpf-button-primary-background-color-disabled: var(--rpf-grey-200);
+    --rpf-button-primary-color-disabled: var(--editor-color-layer-3);
+    --rpf-button-primary-color-disabled-focus: var(--editor-color-theme);
+    --rpf-button-primary-background-color-hover: var(--rpf-navy-600);
+
+    // Secondary button
+    --rpf-button-secondary-text-color: var(--rpf-white);
+    --rpf-button-secondary-background-color: var(--editor-color-layer-2);
+    --rpf-button-secondary-background-color-active: var(--rpf-navy-200);
+    --rpf-button-secondary-color-disabled-background: var(--editor-color-layer-3);
+    --rpf-button-secondary-background-color-hover: var(--editor-color-outline);
+    --rpf-button-secondary-border-color: var(--editor-color-theme);
+    --rpf-button-secondary-border-color-hover: var(--editor-color-theme);
+    --rpf-button-secondary-color-disabled: var(--rpf-grey-100);
+    --rpf-button-secondary-color: var(--rpf-white);
+
+    // Tertiary button
+    --rpf-button-tertiary-text-color-hover: var(--rpf-grey-200);
+    --rpf-button-tertiary-danger-text-color: var(--rpf-red-600);
+    --rpf-button-tertiary-danger-background-color-hover: rgba(255, 255, 255, 0.1);
+    --rpf-button-tertiary-danger-background-color-active: rgba(255, 255, 255, 0.15);
   }
 }
+
+
diff --git a/src/assets/stylesheets/index.scss b/src/assets/stylesheets/index.scss
index 79b1013a9..13cd28c5f 100644
--- a/src/assets/stylesheets/index.scss
+++ b/src/assets/stylesheets/index.scss
@@ -1,173 +1,50 @@
-@use "./rpf_design_system/colours" as *;
-@use "./rpf_design_system/spacing" as *;
-@use "./settings/fonts" as fonts;
-
-html,
-body {
-  margin: 0;
-}
-
-:root {
-  --editor-font-family-sans-serif: #{fonts.$font-family-sans-serif};
-  --editor-font-family-monospace: #{fonts.$font-family-monospace};
-}
-
-body {
-  font-family: var(--editor-font-family-sans-serif);
-  -webkit-font-smoothing: antialiased;
-  -moz-osx-font-smoothing: grayscale;
-}
-
-code {
-  font-family: var(--editor-font-family-monospace);
-}
+#wc.--use-editor-styles.--light {
+  --editor-color-theme: var(--rpf-teal-800);
+  --editor-color-theme-secondary: var(--rpf-teal-900);
+  --editor-color-theme-tertiary: var(--rpf-teal-100);
+
+  --rpf-files-list-item-active: var(--rpf-teal-secondary-tertiary-active);
+  --rpf-files-list-item-hover: var(--rpf-teal-secondary-tertiary-hover);
+  --rpf-tab-border-bottom-selected: var(--editor-color-theme-secondary);
+  --sidebar-option-selected-background-hover: var(--rpf-teal-200);
 
-#app {
-  min-block-size: 100dvh;
+  .btn,
+  .rpf-button {
+    --rpf-button-primary-background-color: var(--editor-color-theme);
+    --rpf-button-primary-background-color-focus: var(--editor-color-theme);
+    --rpf-button-primary-background-color-hover: var(--editor-color-theme-secondary);
+    --rpf-button-primary-background-color-active: var(--rpf-teal-600);
+    --rpf-button-primary-background-color-disabled: var(--rpf-teal-200);
+    --rpf-button-primary-text-color: var(--rpf-black);
+
+    --rpf-button-secondary-background-color: var(--editor-color-theme);
+    --rpf-button-secondary-background-color-hover: var(--editor-color-theme-tertiary);
+    --rpf-button-secondary-border-color: var(--editor-color-theme);
+    --rpf-button-secondary-border-color-hover: var(--editor-color-theme-secondary);
+    --rpf-button-secondary-background-color-active: var(--editor-color-theme-secondary);
+    --rpf-button-secondary-text-color: var(--rpf-black);
+  }
 }
 
-.--light, #wc.--light {
-  --editor-color-layer-1: #{$rpf-teal-100};
-  --editor-color-layer-2: #{$rpf-black};
-  --editor-color-layer-3: #{$rpf-white};
-  --editor-color-outline: #{$rpf-grey-150};
-  --editor-color-theme: #{$rpf-teal-800};
-  --editor-color-theme-secondary: #{$rpf-teal-900};
-  --editor-color-theme-tertiary: #{$rpf-teal-100};
-  --editor-color-text: #{$rpf-text-primary};
-  --editor-color-text-secondary: #{$rpf-text-secondary};
-  --rpf-files-list-item-active: #{$rpf-teal-secondary-tertiary-active};
-  --rpf-files-list-item-hover: #{$rpf-teal-secondary-tertiary-hover};
-  --rpf-tab-button-hover: var(--rpf-grey-100);
-  --rpf-tab-button-background: inherit;
-  --rpf-tab-border-bottom-selected: var(--rpf-teal-900);
-  --sidebar-border: var(--rpf-grey-150);
-  --sidebar-background: var(--rpf-white);
-  --sidebar-background-selected: var(--rpf-off-white);
-  --sidebar-panel-background: var(--rpf-white);
-  --sidebar-option-hover: var(--rpf-grey-100);
-  --sidebar-option-selected-icon: var(--rpf-black);
-  --sidebar-option-selected-border: var(--editor-color-theme);
-  --sidebar-option-selected-background: var(--editor-color-theme-tertiary);
-  --sidebar-option-selected-background-hover: var(--rpf-teal-200);
-}
+#wc.--use-editor-styles.--dark {
+  --editor-color-theme: var(--rpf-teal-800);
+  --editor-color-theme-secondary: var(--rpf-teal-400);
+  --editor-color-theme-tertiary: var(--rpf-teal-900);
 
-.--dark, #wc.--dark {
-  --editor-color-layer-1: #{$rpf-grey-850};
-  --editor-color-layer-2: #{$rpf-grey-800};
-  --editor-color-layer-3: #{$rpf-grey-700};
-  --editor-color-outline: #{$rpf-grey-600};
-  --editor-color-theme: #{$rpf-teal-400};
-  --editor-color-theme-secondary: #{$rpf-teal-400};
-  --editor-color-theme-tertiary: #{$rpf-teal-900};
-  --editor-color-text: #{$rpf-white};
-  --editor-color-text-secondary: #{$rpf-text-secondary-darkmode};
-  --rpf-files-list-item-active: #{$rpf-grey-secondary-tertiary-active};
-  --rpf-files-list-item-hover: #{$rpf-grey-secondary-tertiary-hover};
-  --rpf-tab-button-hover: var(--rpf-grey-900);
-  --rpf-tab-button-background: var(--rpf-grey-800);
-  --rpf-tab-border-bottom-selected: var(--rpf-teal-800);
-  --sidebar-border: var(--rpf-grey-600);
-  --sidebar-background: var(--rpf-grey-800);
-  --sidebar-background-selected: var(--rpf-grey-800);
-  --sidebar-panel-background: var(--rpf-grey-700);
-  --sidebar-option-hover: var(--rpf-grey-600);
-  --sidebar-option-selected-icon: var(--rpf-white);
-  --sidebar-option-selected-border: var(--editor-color-theme);
-  --sidebar-option-selected-background: var(--editor-color-theme-tertiary);
-  --sidebar-option-selected-background-hover: var(--rpf-teal-800);
+  --rpf-tab-border-bottom-selected: var(--editor-color-theme);
+  --sidebar-option-selected-background-hover: var(--rpf-teal-950);
 
   .btn,
   .rpf-button {
-    --rpf-button-primary-background-color: var(--rpf-teal-400);
-    --rpf-button-primary-background-color-focus: var(--rpf-teal-400);
+    --rpf-button-primary-background-color: var(--editor-color-theme-secondary);
+    --rpf-button-primary-background-color-focus: var(--editor-color-theme-secondary);
     --rpf-button-primary-background-color-active: var(--rpf-teal-200);
-    --rpf-button-primary-background-color-disabled: var(--rpf-grey-200);
-    --rpf-button-primary-color-disabled: var(--rpf-grey-700);
-    --rpf-button-primary-color-disabled-focus: var(--rpf-teal-400);
+    --rpf-button-primary-color-disabled-focus: var(--editor-color-theme-secondary);
     --rpf-button-primary-background-color-hover: var(--rpf-teal-600);
+    --rpf-button-primary-text-color: var(--rpf-black);
 
-    --rpf-button-secondary-background-color: var(--rpf-grey-800);
     --rpf-button-secondary-background-color-active: var(--rpf-teal-200);
-    --rpf-button-secondary-color-disabled-background: var(--rpf-grey-700);
-    --rpf-button-secondary-background-color-hover: var(--rpf-grey-600);
-    --rpf-button-secondary-border-color-hover: var(--rpf-teal-400);
-    --rpf-button-secondary-color-disabled: var(--rpf-grey-100);
-    --rpf-button-secondary-color: var(--rpf-white);
-    --rpf-button-secondary-text-color: var(--rpf-white);
-
-    --rpf-button-tertiary-text-color-hover: var(--rpf-grey-200);
-
-    --rpf-button-tertiary-danger-text-color: var(--rpf-red-600);
-    --rpf-button-tertiary-danger-background-color-hover: rgba(255, 255, 255, 0.1);
-    --rpf-button-tertiary-danger-background-color-active: rgba(255, 255, 255, 0.15);
-  }
-
-  .rpf-button--secondary {
-    border-color: var(--rpf-teal-400);
-  }
-}
-
-.btn,
-.rpf-button {
-  --rpf-button-primary-background-color: var(--rpf-teal-800);
-  --rpf-button-primary-background-color-focus: var(--rpf-teal-800);
-  --rpf-button-primary-background-color-hover: var(--rpf-teal-900);
-  --rpf-button-primary-background-color-active: var(--rpf-teal-600);
-  --rpf-button-primary-background-color-disabled: var(--rpf-teal-200);
-  --rpf-button-primary-color-disabled: var(--rpf-grey-600);
-  --rpf-button-primary-text-color: var(--rpf-black);
-
-  --rpf-button-secondary-background-color: var(--rpf-teal-800);
-  --rpf-button-secondary-background-color-focus: #{$rpf-brand-raspberry}; // scss var?
-  --rpf-button-secondary-background-color-hover: var(--rpf-teal-100);
-  --rpf-button-secondary-border-color-hover: var(--rpf-teal-900);
-  --rpf-button-secondary-background-color-active: var(--rpf-teal-900);
-  --rpf-button-secondary-background-color-disabled: var(--rpf-grey-50); // might not exist
-  --rpf-button-secondary-text-color: var(--rpf-black);
-
-  --rpf-button-tertiary-text-color-hover: var(--rpf-grey-600);
-
-  --rpf-button-tertiary-danger-text-color: var(--rpf-alert-error);
-  --rpf-button-tertiary-danger-background-color-hover: rgba(0, 0, 0, 0.03);
-  --rpf-button-tertiary-danger-background-color-active: rgba(0, 0, 0, 0.05);
-
-  .rpf-button--secondary {
-    border-color: var(--rpf-teal-800);
-  }
-}
-
-.select-buttons__tick--selected {
-  --rpf-select-buttons-tick-color: var(--rpf-black);
-}
-
-.modal-overlay {
-  --rpf-input-active-border: var(--editor-color-theme);
-}
-
-.project-wrapper {
-  --project-wrapper-grid-gap: #{$space-0-5};
-}
-
-.proj-editor-wrapper {
-  --project-editor-wrapper-grid-gap: #{$space-1};
-}
-
-.project-instructions {
-  pre {
-    --code-block-scrollbar-color: auto;
-    --code-background-color: #{$rpf-grey-700};
-    --code-text-color: #{$rpf-white};
-  }
-
-  .line-highlight {
-    --code-block-line-highlight-color: #{$rpf-white};
+    --rpf-button-secondary-border-color-hover: var(--editor-color-theme-secondary);
   }
 }
 
-.btn--tertiary {
-  &:hover,
-  .btn-outer:hover & {
-    --tertiary-btn-hover-color: inherit;
-  }
-}
diff --git a/src/containers/WebComponentLoader.jsx b/src/containers/WebComponentLoader.jsx
index f468a97bd..188d235df 100644
--- a/src/containers/WebComponentLoader.jsx
+++ b/src/containers/WebComponentLoader.jsx
@@ -220,7 +220,12 @@ const WebComponentLoader = (props) => {
         {hostStyles && <style>{hostStyles}</style>}
         <Style>
           {internalStyles.toString()}
-          <div id="wc" className={`--${cookies.theme || themeDefault}`}>
+          <div
+            id="wc"
+            className={`--${cookies.theme || themeDefault}${
+              useEditorStyles ? " --use-editor-styles" : ""
+            }`}
+          >
             <ToastContainer
               enableMultiContainer
               containerId="top-center"
diff --git a/src/containers/WebComponentLoader.test.js b/src/containers/WebComponentLoader.test.js
index 569806db3..7a7599238 100644
--- a/src/containers/WebComponentLoader.test.js
+++ b/src/containers/WebComponentLoader.test.js
@@ -335,6 +335,52 @@ describe("When no user is in state", () => {
       );
       expect(editorStyles).not.toBeNull();
     });
+
+    test("Adds editor override marker class when useEditorStyles is true", () => {
+      const { container } = render(
+        <Provider store={store}>
+          <CookiesProvider cookies={cookies}>
+            <WebComponentLoader
+              code={code}
+              identifier={identifier}
+              senseHatAlwaysEnabled={true}
+              instructions={instructions}
+              authKey={authKey}
+              theme="light"
+              useEditorStyles={true}
+            />
+          </CookiesProvider>
+        </Provider>,
+      );
+
+      expect(container.querySelector("#wc")).toHaveClass(
+        "--light",
+        "--use-editor-styles",
+      );
+    });
+
+    test("Does not add editor override marker class when useEditorStyles is false", () => {
+      const { container } = render(
+        <Provider store={store}>
+          <CookiesProvider cookies={cookies}>
+            <WebComponentLoader
+              code={code}
+              identifier={identifier}
+              senseHatAlwaysEnabled={true}
+              instructions={instructions}
+              authKey={authKey}
+              theme="dark"
+              useEditorStyles={false}
+            />
+          </CookiesProvider>
+        </Provider>,
+      );
+
+      expect(container.querySelector("#wc")).toHaveClass("--dark");
+      expect(container.querySelector("#wc")).not.toHaveClass(
+        "--use-editor-styles",
+      );
+    });
   });
 
   describe("with assetsIdentifier set", () => {