diff --git a/src/lib/components/modals/EventJsonModal.svelte b/src/lib/components/modals/EventJsonModal.svelte
index f80c0be..a648a23 100644
--- a/src/lib/components/modals/EventJsonModal.svelte
+++ b/src/lib/components/modals/EventJsonModal.svelte
@@ -1,6 +1,9 @@
 <script lang="ts">
   import type { NostrEvent } from '../../types/nostr.js';
   import Icon from '../ui/Icon.svelte';
+  // @ts-ignore - highlight.js default export works at runtime
+  import hljs from 'highlight.js';
+  import 'highlight.js/styles/vs2015.css';
 
   interface Props {
     open?: boolean;
@@ -10,6 +13,22 @@
   let { open = $bindable(false), event = $bindable(null) }: Props = $props();
   let jsonText = $derived(event ? JSON.stringify(event, null, 2) : '');
   let copied = $state(false);
+  let jsonPreviewRef: HTMLElement | null = $state(null);
+  
+  // Highlight JSON when it changes
+  $effect(() => {
+    if (jsonPreviewRef && jsonText && jsonPreviewRef instanceof HTMLElement) {
+      try {
+        const highlighted = hljs.highlight(jsonText, { language: 'json' }).value;
+        jsonPreviewRef.innerHTML = highlighted;
+        jsonPreviewRef.className = 'hljs language-json';
+      } catch (err) {
+        // Fallback to plain text if highlighting fails
+        jsonPreviewRef.textContent = jsonText;
+        jsonPreviewRef.className = 'language-json';
+      }
+    }
+  });
 
   function close() {
     open = false;
@@ -59,11 +78,7 @@
       </div>
 
       <div class="modal-body">
-        <textarea
-          class="json-textarea"
-          readonly
-          value={jsonText}
-        ></textarea>
+        <pre class="json-preview"><code bind:this={jsonPreviewRef} class="language-json">{jsonText}</code></pre>
       </div>
 
       <div class="modal-footer">
@@ -195,40 +210,47 @@
     overflow: auto;
   }
 
-  .json-textarea {
-    width: 100%;
-    min-height: 400px;
-    font-family: 'Courier New', monospace;
-    font-size: 0.875rem;
-    padding: 0.75rem;
-    border: 1px solid var(--fog-border, #e5e7eb);
+  .json-preview {
+    background: #1e1e1e !important; /* VS Code dark background, same as code blocks */
+    border: 1px solid #3e3e3e;
     border-radius: 4px;
-    background: var(--fog-bg, #ffffff);
-    color: var(--fog-text, #1f2937);
-    resize: vertical;
+    padding: 1rem;
+    margin: 0;
+    overflow-x: auto;
+    max-height: 60vh;
+  }
+
+  .json-preview code {
+    display: block;
+    overflow-x: auto;
+    padding: 0;
+    background: transparent !important;
+    color: #d4d4d4; /* VS Code text color */
+    font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;
+    font-size: 0.875rem;
+    line-height: 1.5;
   }
 
   @media (max-width: 768px) {
-    .json-textarea {
-      min-height: 300px;
+    .json-preview {
+      padding: 0.75rem;
+    }
+
+    .json-preview code {
       font-size: 0.8125rem;
-      padding: 0.5rem;
     }
   }
 
   @media (max-width: 640px) {
-    .json-textarea {
-      min-height: calc(100vh - 200px);
-      font-size: 0.75rem;
+    .json-preview {
       padding: 0.5rem;
       border-radius: 0;
+      max-height: calc(100vh - 200px);
     }
-  }
 
-  :global(.dark) .json-textarea {
-    background: var(--fog-dark-bg, #0f172a);
-    border-color: var(--fog-dark-border, #374151);
-    color: var(--fog-dark-text, #f1f5f9);
+    .json-preview code {
+      font-size: 0.75rem;
+    }
   }
 
   .modal-footer {
diff --git a/src/lib/components/preferences/ThemeToggle.svelte b/src/lib/components/preferences/ThemeToggle.svelte
index c5f6b18..5f56626 100644
--- a/src/lib/components/preferences/ThemeToggle.svelte
+++ b/src/lib/components/preferences/ThemeToggle.svelte
@@ -4,20 +4,30 @@
 
   let isDark = $state(false);
 
-  onMount(() => {
-    // Check localStorage and system preference
-    const stored = localStorage.getItem('theme');
-    const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
-    isDark = stored === 'dark' || (!stored && prefersDark);
-    updateTheme();
-  });
+  function getDesignTheme(): string {
+    if (typeof window === 'undefined') return 'fog';
+    return document.documentElement.getAttribute('data-design-theme') || localStorage.getItem('designTheme') || 'fog';
+  }
 
   function toggleTheme() {
+    const designTheme = getDesignTheme();
+    // Terminal theme always uses dark mode - don't allow toggling
+    if (designTheme === 'terminal') {
+      return;
+    }
     isDark = !isDark;
     updateTheme();
   }
 
   function updateTheme() {
+    const designTheme = getDesignTheme();
+    // Terminal theme always uses dark mode
+    if (designTheme === 'terminal') {
+      document.documentElement.classList.add('dark');
+      // Don't update localStorage for terminal theme - it's always dark
+      return;
+    }
+
     if (isDark) {
       document.documentElement.classList.add('dark');
       localStorage.setItem('theme', 'dark');
@@ -26,6 +36,63 @@
       localStorage.setItem('theme', 'light');
     }
   }
+
+  onMount(() => {
+    if (typeof window === 'undefined') return;
+
+    // Check if terminal theme (always dark)
+    const designTheme = getDesignTheme();
+    if (designTheme === 'terminal') {
+      isDark = true;
+      updateTheme();
+    } else {
+      // Check localStorage and system preference
+      const stored = localStorage.getItem('theme');
+      const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+      isDark = stored === 'dark' || (!stored && prefersDark);
+      updateTheme();
+    }
+
+    // Watch for design theme and storage changes
+    // Listen for storage changes to sync theme across tabs
+    const handleStorageChange = (e: StorageEvent) => {
+      if (e.key === 'theme' || e.key === 'designTheme') {
+        const designTheme = getDesignTheme();
+        if (designTheme === 'terminal') {
+          isDark = true;
+        } else if (e.key === 'theme') {
+          isDark = e.newValue === 'dark';
+        } else {
+          // Design theme changed - re-read theme
+          const stored = localStorage.getItem('theme');
+          const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+          isDark = stored === 'dark' || (!stored && prefersDark);
+        }
+        updateTheme();
+      }
+    };
+
+    // Watch for design theme attribute changes
+    const observer = new MutationObserver(() => {
+      const designTheme = getDesignTheme();
+      if (designTheme === 'terminal') {
+        isDark = true;
+        updateTheme();
+      }
+    });
+
+    observer.observe(document.documentElement, {
+      attributes: true,
+      attributeFilter: ['data-design-theme']
+    });
+
+    window.addEventListener('storage', handleStorageChange);
+
+    return () => {
+      observer.disconnect();
+      window.removeEventListener('storage', handleStorageChange);
+    };
+  });
 </script>
 
 <button
diff --git a/src/lib/components/profile/ProfileMenu.svelte b/src/lib/components/profile/ProfileMenu.svelte
index d93492c..f4bf5c1 100644
--- a/src/lib/components/profile/ProfileMenu.svelte
+++ b/src/lib/components/profile/ProfileMenu.svelte
@@ -9,6 +9,9 @@
   import type { NostrEvent } from '../../types/nostr.js';
   import { toggleMute, toggleFollow, isMuted, isFollowed } from '../../services/user-actions.js';
   import Icon from '../ui/Icon.svelte';
+  // @ts-ignore - highlight.js default export works at runtime
+  import hljs from 'highlight.js';
+  import 'highlight.js/styles/vs2015.css';
 
   interface Props {
     pubkey: string;
@@ -26,6 +29,25 @@
   let muting = $state(false);
   let following = $state(false);
   let showJsonModal = $state(false);
+  let jsonPreviewRef: HTMLElement | null = $state(null);
+  
+  // Highlight JSON when profileEvent or showJsonModal changes
+  $effect(() => {
+    if (jsonPreviewRef && profileEvent && jsonPreviewRef instanceof HTMLElement && showJsonModal) {
+      try {
+        const jsonText = JSON.stringify(profileEvent, null, 2);
+        const highlighted = hljs.highlight(jsonText, { language: 'json' }).value;
+        jsonPreviewRef.innerHTML = highlighted;
+        jsonPreviewRef.className = 'hljs language-json';
+      } catch (err) {
+        // Fallback to plain text if highlighting fails
+        if (profileEvent) {
+          jsonPreviewRef.textContent = JSON.stringify(profileEvent, null, 2);
+          jsonPreviewRef.className = 'language-json';
+        }
+      }
+    }
+  });
 
   let isLoggedIn = $derived(sessionManager.isLoggedIn());
   let currentUserPubkey = $derived(sessionManager.getCurrentPubkey());
@@ -442,7 +464,7 @@
         </div>
         <div class="json-modal-body">
           {#if profileEvent}
-            <pre class="json-content">{JSON.stringify(profileEvent, null, 2)}</pre>
+            <pre class="json-content"><code bind:this={jsonPreviewRef} class="language-json">{JSON.stringify(profileEvent, null, 2)}</code></pre>
           {:else}
             <p class="text-fog-text-light dark:text-fog-dark-text-light">Loading profile event...</p>
           {/if}
@@ -688,18 +710,23 @@
   }
 
   .json-content {
+    background: #1e1e1e !important; /* VS Code dark background, same as code blocks */
+    border: 1px solid #3e3e3e;
+    border-radius: 0.25rem;
+    padding: 1rem;
     margin: 0;
-    font-family: 'Courier New', monospace;
-    font-size: 0.875rem;
-    line-height: 1.5;
-    color: var(--fog-text, #1f2937);
-    white-space: pre-wrap;
-    word-break: break-word;
-    overflow-wrap: break-word;
+    overflow-x: auto;
   }
 
-  :global(.dark) .json-content {
-    color: var(--fog-dark-text, #f9fafb);
+  .json-content code {
+    display: block;
+    overflow-x: auto;
+    padding: 0;
+    background: transparent !important;
+    color: #d4d4d4; /* VS Code text color */
+    font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;
+    font-size: 0.875rem;
+    line-height: 1.5;
   }
 
   @media (max-width: 640px) {
@@ -721,6 +748,10 @@
     }
 
     .json-content {
+      padding: 0.75rem;
+    }
+
+    .json-content code {
       font-size: 0.75rem;
     }
   }
diff --git a/src/lib/components/write/AdvancedEditor.svelte b/src/lib/components/write/AdvancedEditor.svelte
index 25eff88..8b292ed 100644
--- a/src/lib/components/write/AdvancedEditor.svelte
+++ b/src/lib/components/write/AdvancedEditor.svelte
@@ -19,6 +19,9 @@
   import MediaViewer from '../content/MediaViewer.svelte';
   import type { NostrEvent } from '../../types/nostr.js';
   import Icon from '../ui/Icon.svelte';
+  // @ts-ignore - highlight.js default export works at runtime
+  import hljs from 'highlight.js';
+  import 'highlight.js/styles/vs2015.css';
 
   interface Props {
     value: string;
@@ -46,6 +49,22 @@
   let previewContent = $state<string>('');
   let previewEvent = $state<NostrEvent | null>(null);
   let eventJson = $state('{}');
+  let jsonPreviewRef: HTMLElement | null = $state(null);
+  
+  // Highlight JSON when it changes
+  $effect(() => {
+    if (jsonPreviewRef && eventJson && jsonPreviewRef instanceof HTMLElement) {
+      try {
+        const highlighted = hljs.highlight(eventJson, { language: 'json' }).value;
+        jsonPreviewRef.innerHTML = highlighted;
+        jsonPreviewRef.className = 'hljs language-json';
+      } catch (err) {
+        // Fallback to plain text if highlighting fails
+        jsonPreviewRef.textContent = eventJson;
+        jsonPreviewRef.className = 'language-json';
+      }
+    }
+  });
   
   // Media viewer state for preview
   let mediaViewerOpen = $state(false);
@@ -1121,7 +1140,7 @@
         </button>
       </div>
       <div class="modal-body">
-        <pre class="json-preview">{eventJson}</pre>
+        <pre class="json-preview"><code bind:this={jsonPreviewRef} class="language-json">{eventJson}</code></pre>
       </div>
       <div class="modal-footer">
         <button onclick={() => {
@@ -1492,20 +1511,32 @@
   }
 
   .json-preview {
-    background: var(--fog-highlight, #f3f4f6);
-    padding: 1rem;
+    background: #1e1e1e !important; /* VS Code dark background, same as code blocks */
+    border: 1px solid #3e3e3e;
     border-radius: 0.25rem;
-    overflow: auto;
-    font-family: 'SF Mono', Monaco, Inconsolata, 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;
-    font-size: 0.875rem;
-    line-height: 1.6;
-    color: var(--fog-text, #1f2937);
+    padding: 1rem;
+    margin: 0;
+    overflow-x: auto;
     max-height: 60vh;
   }
 
+  .json-preview code {
+    display: block;
+    overflow-x: auto;
+    padding: 0;
+    background: transparent !important;
+    color: #d4d4d4; /* VS Code text color */
+    font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;
+    font-size: 0.875rem;
+    line-height: 1.5;
+  }
+
   @media (max-width: 768px) {
     .json-preview {
       padding: 0.75rem;
+    }
+
+    .json-preview code {
       font-size: 0.8125rem;
     }
   }
@@ -1513,15 +1544,13 @@
   @media (max-width: 640px) {
     .json-preview {
       padding: 0.5rem;
-      font-size: 0.75rem;
       border-radius: 0.25rem;
       max-height: calc(100vh - 200px);
     }
-  }
 
-  :global(.dark) .json-preview {
-    background: var(--fog-dark-highlight, #374151);
-    color: var(--fog-dark-text, #f9fafb);
+    .json-preview code {
+      font-size: 0.75rem;
+    }
   }
 
   .preview-modal {
diff --git a/src/lib/components/write/CreateEventForm.svelte b/src/lib/components/write/CreateEventForm.svelte
index 6e3cb45..e79a4c9 100644
--- a/src/lib/components/write/CreateEventForm.svelte
+++ b/src/lib/components/write/CreateEventForm.svelte
@@ -19,6 +19,9 @@
   import { autoExtractTags, ensureDTagForParameterizedReplaceable } from '../../services/auto-tagging.js';
   import { isParameterizedReplaceableKind } from '../../types/kind-lookup.js';
   import Icon from '../ui/Icon.svelte';
+  // @ts-ignore - highlight.js default export works at runtime
+  import hljs from 'highlight.js';
+  import 'highlight.js/styles/vs2015.css';
 
   const SUPPORTED_KINDS = getWritableKinds();
 
@@ -118,6 +121,22 @@
   let richTextEditorRef: { clearUploadedFiles: () => void; getUploadedFiles: () => Array<{ url: string; imetaTag: string[] }> } | null = $state(null);
   let uploadedFiles: Array<{ url: string; imetaTag: string[] }> = $state([]);
   let eventJson = $state('{}');
+  let jsonPreviewRef: HTMLElement | null = $state(null);
+  
+  // Highlight JSON when it changes
+  $effect(() => {
+    if (jsonPreviewRef && eventJson && jsonPreviewRef instanceof HTMLElement) {
+      try {
+        const highlighted = hljs.highlight(eventJson, { language: 'json' }).value;
+        jsonPreviewRef.innerHTML = highlighted;
+        jsonPreviewRef.className = 'hljs language-json';
+      } catch (err) {
+        // Fallback to plain text if highlighting fails
+        jsonPreviewRef.textContent = eventJson;
+        jsonPreviewRef.className = 'language-json';
+      }
+    }
+  });
   
   const isUnknownKind = $derived(selectedKind === -1);
   const effectiveKind = $derived(isUnknownKind ? (parseInt(customKindId) || 1) : selectedKind);
@@ -721,7 +740,7 @@
           </button>
         </div>
         <div class="modal-body">
-          <pre class="json-preview">{eventJson}</pre>
+          <pre class="json-preview"><code bind:this={jsonPreviewRef} class="language-json">{eventJson}</code></pre>
         </div>
         <div class="modal-footer">
           <button onclick={() => {
@@ -1565,15 +1584,23 @@
   }
 
   .json-preview {
-    background: #1e293b;
-    color: #f1f5f9;
-    padding: 1rem;
+    background: #1e1e1e !important; /* VS Code dark background, same as code blocks */
+    border: 1px solid #3e3e3e;
     border-radius: 0.5rem;
+    padding: 1rem;
+    margin: 0;
     overflow-x: auto;
-    font-family: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
+  }
+
+  .json-preview code {
+    display: block;
+    overflow-x: auto;
+    padding: 0;
+    background: transparent !important;
+    color: #d4d4d4; /* VS Code text color */
+    font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;
     font-size: 0.875rem;
     line-height: 1.5;
-    margin: 0;
   }
 
   @media (max-width: 768px) {
diff --git a/src/lib/modules/comments/CommentForm.svelte b/src/lib/modules/comments/CommentForm.svelte
index 08cd7da..fb9b84b 100644
--- a/src/lib/modules/comments/CommentForm.svelte
+++ b/src/lib/modules/comments/CommentForm.svelte
@@ -16,6 +16,9 @@
   import { shouldIncludeClientTag } from '../../services/client-tag-preference.js';
   import { cacheEvent } from '../../services/cache/event-cache.js';
   import { autoExtractTags } from '../../services/auto-tagging.js';
+  // @ts-ignore - highlight.js default export works at runtime
+  import hljs from 'highlight.js';
+  import 'highlight.js/styles/vs2015.css';
 
   interface Props {
     threadId: string; // The root event ID
@@ -96,6 +99,23 @@
   }
   let uploadedFiles: Array<{ url: string; imetaTag: string[] }> = $state([]);
   let eventJson = $state('{}');
+  let jsonPreviewRef: HTMLElement | null = $state(null);
+  
+  // Highlight JSON when it changes
+  $effect(() => {
+    if (jsonPreviewRef && eventJson && jsonPreviewRef instanceof HTMLElement) {
+      try {
+        const highlighted = hljs.highlight(eventJson, { language: 'json' }).value;
+        jsonPreviewRef.innerHTML = highlighted;
+        jsonPreviewRef.className = 'hljs language-json';
+      } catch (err) {
+        // Fallback to plain text if highlighting fails
+        jsonPreviewRef.textContent = eventJson;
+        jsonPreviewRef.className = 'language-json';
+      }
+    }
+  });
+  
   const isLoggedIn = $derived(sessionManager.isLoggedIn());
 
   // Only show GIF/emoji buttons for non-kind-11 events (kind 1 replies and kind 1111 comments)
@@ -518,7 +538,7 @@
           <button onclick={() => showJsonModal = false} class="close-button">×</button>
         </div>
         <div class="modal-body">
-          <pre class="json-preview">{eventJson}</pre>
+          <pre class="json-preview"><code bind:this={jsonPreviewRef} class="language-json">{eventJson}</code></pre>
         </div>
         <div class="modal-footer">
           <button onclick={() => {
@@ -723,20 +743,31 @@
   }
 
   .json-preview {
-    background: #1e293b;
-    color: #f1f5f9;
-    padding: 1rem;
+    background: #1e1e1e !important; /* VS Code dark background, same as code blocks */
+    border: 1px solid #3e3e3e;
     border-radius: 0.5rem;
+    padding: 1rem;
+    margin: 0;
     overflow-x: auto;
-    font-family: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
+  }
+
+  .json-preview code {
+    display: block;
+    overflow-x: auto;
+    padding: 0;
+    background: transparent !important;
+    color: #d4d4d4; /* VS Code text color */
+    font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;
     font-size: 0.875rem;
     line-height: 1.5;
-    margin: 0;
   }
 
   @media (max-width: 768px) {
     .json-preview {
       padding: 0.75rem;
+    }
+
+    .json-preview code {
       font-size: 0.8125rem;
     }
   }
@@ -744,9 +775,12 @@
   @media (max-width: 640px) {
     .json-preview {
       padding: 0.5rem;
-      font-size: 0.75rem;
       border-radius: 0.25rem;
     }
+
+    .json-preview code {
+      font-size: 0.75rem;
+    }
   }
 
   .preview-modal {
diff --git a/src/lib/modules/rss/RSSCommentForm.svelte b/src/lib/modules/rss/RSSCommentForm.svelte
index c5c56b9..87b12b5 100644
--- a/src/lib/modules/rss/RSSCommentForm.svelte
+++ b/src/lib/modules/rss/RSSCommentForm.svelte
@@ -16,6 +16,9 @@
   import { autoExtractTags } from '../../services/auto-tagging.js';
   import type { NostrEvent } from '../../types/nostr.js';
   import { cleanTrackingParams } from '../../utils/url-cleaner.js';
+  // @ts-ignore - highlight.js default export works at runtime
+  import hljs from 'highlight.js';
+  import 'highlight.js/styles/vs2015.css';
 
   interface Props {
     url: string; // The RSS item URL
@@ -95,6 +98,23 @@
   }
   let uploadedFiles: Array<{ url: string; imetaTag: string[] }> = $state([]);
   let eventJson = $state('{}');
+  let jsonPreviewRef: HTMLElement | null = $state(null);
+  
+  // Highlight JSON when it changes
+  $effect(() => {
+    if (jsonPreviewRef && eventJson && jsonPreviewRef instanceof HTMLElement) {
+      try {
+        const highlighted = hljs.highlight(eventJson, { language: 'json' }).value;
+        jsonPreviewRef.innerHTML = highlighted;
+        jsonPreviewRef.className = 'hljs language-json';
+      } catch (err) {
+        // Fallback to plain text if highlighting fails
+        jsonPreviewRef.textContent = eventJson;
+        jsonPreviewRef.className = 'language-json';
+      }
+    }
+  });
+  
   const isLoggedIn = $derived(sessionManager.isLoggedIn());
 
   async function publishComment() {
@@ -392,7 +412,7 @@
           <button onclick={() => showJsonModal = false} class="close-button">×</button>
         </div>
         <div class="modal-body">
-          <pre class="json-preview">{eventJson}</pre>
+          <pre class="json-preview"><code bind:this={jsonPreviewRef} class="language-json">{eventJson}</code></pre>
         </div>
         <div class="modal-footer">
           <button onclick={() => {
@@ -656,19 +676,31 @@
   }
 
   .json-preview {
-    background: var(--fog-highlight, #f3f4f6);
-    padding: 1rem;
+    background: #1e1e1e !important; /* VS Code dark background, same as code blocks */
+    border: 1px solid #3e3e3e;
     border-radius: 0.25rem;
+    padding: 1rem;
+    margin: 0;
     overflow-x: auto;
-    font-family: 'Courier New', monospace;
+  }
+
+  .json-preview code {
+    display: block;
+    overflow-x: auto;
+    padding: 0;
+    background: transparent !important;
+    color: #d4d4d4; /* VS Code text color */
+    font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;
     font-size: 0.875rem;
-    white-space: pre-wrap;
-    word-wrap: break-word;
+    line-height: 1.5;
   }
 
   @media (max-width: 768px) {
     .json-preview {
       padding: 0.75rem;
+    }
+
+    .json-preview code {
       font-size: 0.8125rem;
     }
   }
@@ -676,14 +708,12 @@
   @media (max-width: 640px) {
     .json-preview {
       padding: 0.5rem;
-      font-size: 0.75rem;
       border-radius: 0.25rem;
     }
-  }
 
-  :global(.dark) .json-preview {
-    background: var(--fog-dark-highlight, #374151);
-    color: var(--fog-dark-text, #f9fafb);
+    .json-preview code {
+      font-size: 0.75rem;
+    }
   }
 
   .modal-footer {
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index fdb79d1..e5a20f0 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -17,17 +17,7 @@
 
   // Initialize theme and preferences from localStorage immediately (before any components render)
   if (browser) {
-    // Initialize theme
-    const storedTheme = localStorage.getItem('theme');
-    const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
-    const shouldBeDark = storedTheme === 'dark' || (!storedTheme && prefersDark);
-    if (shouldBeDark) {
-      document.documentElement.classList.add('dark');
-    } else {
-      document.documentElement.classList.remove('dark');
-    }
-
-    // Initialize other preferences
+    // Initialize other preferences first (design theme affects theme)
     const textSize = localStorage.getItem('textSize') || 'medium';
     const lineSpacing = localStorage.getItem('lineSpacing') || 'normal';
     const contentWidth = localStorage.getItem('contentWidth') || 'medium';
@@ -38,6 +28,31 @@
     document.documentElement.setAttribute('data-content-width', contentWidth);
     document.documentElement.setAttribute('data-design-theme', designTheme);
 
+    // Initialize theme (terminal theme always uses dark mode)
+    const storedTheme = localStorage.getItem('theme');
+    const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+    let shouldBeDark: boolean;
+    
+    if (designTheme === 'terminal') {
+      // Terminal theme always uses dark mode
+      shouldBeDark = true;
+    } else if (storedTheme) {
+      shouldBeDark = storedTheme === 'dark';
+    } else {
+      shouldBeDark = prefersDark;
+    }
+    
+    if (shouldBeDark) {
+      document.documentElement.classList.add('dark');
+      // Ensure localStorage is set correctly
+      if (designTheme !== 'terminal') {
+        localStorage.setItem('theme', 'dark');
+      }
+    } else {
+      document.documentElement.classList.remove('dark');
+      localStorage.setItem('theme', 'light');
+    }
+
     // Try to restore session synchronously if possible
     // This ensures session is restored before any components render
     (async () => {
@@ -52,15 +67,67 @@
   }
 
   // Also restore in onMount as fallback
-  onMount(async () => {
-    try {
-      // Only restore if there's no active session
-      // This prevents overwriting sessions that were just created during login
-      if (!sessionManager.isLoggedIn()) {
-        await sessionManager.restoreSession();
-      }
-      
-      if (browser) {
+  onMount(() => {
+    // Set up storage listener synchronously
+    let storageCleanup: (() => void) | undefined;
+    
+    if (browser) {
+      // Listen for storage changes to sync settings across tabs
+      const handleStorageChange = (e: StorageEvent) => {
+        if (e.key === 'theme') {
+          const designTheme = document.documentElement.getAttribute('data-design-theme') || 'fog';
+          if (designTheme === 'terminal') {
+            // Terminal theme always uses dark mode
+            document.documentElement.classList.add('dark');
+          } else if (e.newValue === 'dark') {
+            document.documentElement.classList.add('dark');
+          } else {
+            document.documentElement.classList.remove('dark');
+          }
+        } else if (e.key === 'designTheme') {
+          const newDesignTheme = e.newValue || 'fog';
+          document.documentElement.setAttribute('data-design-theme', newDesignTheme);
+          // Terminal theme always uses dark mode
+          if (newDesignTheme === 'terminal') {
+            document.documentElement.classList.add('dark');
+          } else {
+            // Re-apply theme from localStorage
+            const storedTheme = localStorage.getItem('theme');
+            const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+            const shouldBeDark = storedTheme === 'dark' || (!storedTheme && prefersDark);
+            if (shouldBeDark) {
+              document.documentElement.classList.add('dark');
+            } else {
+              document.documentElement.classList.remove('dark');
+            }
+          }
+        } else if (e.key === 'textSize') {
+          document.documentElement.setAttribute('data-text-size', e.newValue || 'medium');
+        } else if (e.key === 'lineSpacing') {
+          document.documentElement.setAttribute('data-line-spacing', e.newValue || 'normal');
+        } else if (e.key === 'contentWidth') {
+          document.documentElement.setAttribute('data-content-width', e.newValue || 'medium');
+        }
+      };
+
+      window.addEventListener('storage', handleStorageChange);
+
+      // Cleanup
+      storageCleanup = () => {
+        window.removeEventListener('storage', handleStorageChange);
+      };
+    }
+
+    // Async operations
+    (async () => {
+      try {
+        // Only restore if there's no active session
+        // This prevents overwriting sessions that were just created during login
+        if (!sessionManager.isLoggedIn()) {
+          await sessionManager.restoreSession();
+        }
+        
+        if (browser) {
         // Check for post-update redirect
         const postUpdateRedirect = sessionStorage.getItem('postUpdateRedirect');
         if (postUpdateRedirect) {
@@ -99,9 +166,13 @@
       preloadGifs().catch(() => {
         // Non-critical, ignore errors
       });
-    } catch (error) {
-      console.error('Failed to restore session:', error);
-    }
+      } catch (error) {
+        console.error('Failed to restore session:', error);
+      }
+    })();
+
+    // Return cleanup function
+    return storageCleanup;
   });
 
   function handleUpdateComplete() {