diff --git a/src/app.css b/src/app.css
index 5b2e466..de520b5 100644
--- a/src/app.css
+++ b/src/app.css
@@ -472,7 +472,8 @@ img.emoji-inline {
 }
 
 /* Responsive images and media - max 600px, scale down on smaller screens */
-img:not(.profile-picture):not([alt*="profile" i]):not([alt*="avatar" i]):not([src*="avatar" i]):not([src*="profile" i]):not(.relay-icon):not(.relay-favorite-pic),
+/* Exclude profile pictures, avatars, and emoji images from responsive sizing */
+img:not(.profile-picture):not([alt*="profile" i]):not([alt*="avatar" i]):not([src*="avatar" i]):not([src*="profile" i]):not(.relay-icon):not(.relay-favorite-pic):not(.emoji-inline):not(.avatar),
 video,
 audio {
   max-width: 600px !important;
@@ -482,10 +483,11 @@ audio {
 }
 
 /* Ensure media in markdown content is responsive */
-.markdown-content img,
+/* Exclude profile pictures, avatars, and emoji images from responsive sizing - they should maintain their fixed size */
+.markdown-content img:not(.profile-picture):not([class*="profile"]):not(.emoji-inline):not(.avatar),
 .markdown-content video,
 .markdown-content audio,
-.post-content img,
+.post-content img:not(.profile-picture):not([class*="profile"]):not(.emoji-inline):not(.avatar),
 .post-content video,
 .post-content audio {
   max-width: 600px;
@@ -494,6 +496,22 @@ audio {
   display: block;
 }
 
+/* Ensure avatars in mentions autocomplete are not affected by responsive image styles */
+.mentions-autocomplete img.avatar,
+.mentions-autocomplete .avatar {
+  width: 1.25rem !important;
+  height: 1.25rem !important;
+  min-width: 1.25rem !important;
+  min-height: 1.25rem !important;
+  max-width: 1.25rem !important;
+  max-height: 1.25rem !important;
+  aspect-ratio: 1 / 1 !important;
+  border-radius: 50% !important;
+  object-fit: cover !important;
+  flex-shrink: 0 !important;
+  display: block !important;
+}
+
 /* Media gallery items should also be responsive */
 .media-gallery img,
 .media-gallery video {
diff --git a/src/lib/components/content/MarkdownRenderer.svelte b/src/lib/components/content/MarkdownRenderer.svelte
index 472d2dc..07c5760 100644
--- a/src/lib/components/content/MarkdownRenderer.svelte
+++ b/src/lib/components/content/MarkdownRenderer.svelte
@@ -1037,6 +1037,21 @@
     align-items: center;
   }
 
+  /* Ensure profile pictures in markdown content maintain circular shape and don't stretch */
+  :global(.markdown-content .profile-badge .profile-picture),
+  :global(.markdown-content .profile-badge .profile-placeholder) {
+    width: 1.5rem !important;
+    height: 1.5rem !important;
+    max-width: 1.5rem !important;
+    max-height: 1.5rem !important;
+    min-width: 1.5rem !important;
+    min-height: 1.5rem !important;
+    aspect-ratio: 1 / 1 !important;
+    border-radius: 50% !important;
+    object-fit: cover !important;
+    flex-shrink: 0 !important;
+  }
+
   /* Embedded events should be block-level */
   :global(.markdown-content [data-nostr-event]) {
     display: block;
diff --git a/src/lib/components/content/MentionsAutocomplete.svelte b/src/lib/components/content/MentionsAutocomplete.svelte
index 8c15bef..90c24b9 100644
--- a/src/lib/components/content/MentionsAutocomplete.svelte
+++ b/src/lib/components/content/MentionsAutocomplete.svelte
@@ -26,29 +26,36 @@
       const cursorPos = target.selectionStart || 0;
       
       // Find @ mention starting from cursor backwards
-      // Allow word chars, @, dots, and hyphens to support NIP-05 format (user@domain.com)
+      // We need to find the leftmost @ that could start a mention
       let start = cursorPos - 1;
+      let foundAt = -1;
+      
+      // First, find the leftmost @ going backwards while characters are valid mention chars
+      // This handles cases like @user@domain.com - we want the first @
       while (start >= 0 && /[\w@.-]/.test(text[start])) {
+        if (text[start] === '@') {
+          foundAt = start;
+        }
         start--;
       }
       
-      if (start >= 0 && text[start] === '@') {
-        // Found @ mention
-        mentionStart = start;
-        const mentionText = text.substring(start + 1, cursorPos);
+      // If we found an @ and there's valid mention text after it, show suggestions
+      if (foundAt >= 0) {
+        mentionStart = foundAt;
+        const mentionText = text.substring(foundAt + 1, cursorPos);
         
         // Check if we're still in a valid mention (word chars, @, dots, hyphens)
         // Support both simple handles (@user) and NIP-05 format (@user@domain.com)
         if (mentionText.length > 0 && /^[\w.-]+(@[\w.-]+)?$/.test(mentionText)) {
           query = mentionText;
           updateSuggestions(mentionText);
-          updatePosition(target, start);
+          updatePosition(target, foundAt);
           showSuggestions = true;
         } else if (mentionText.length === 0) {
           // Just @, show all suggestions
           query = '';
           updateSuggestions('');
-          updatePosition(target, start);
+          updatePosition(target, foundAt);
           showSuggestions = true;
         } else {
           showSuggestions = false;
@@ -132,9 +139,21 @@
 
     const suggestion = suggestions[index];
     const handle = suggestion.handle || suggestion.name || suggestion.pubkey.slice(0, 8);
-    const mentionText = `@${handle} `;
     
-    // Replace @mention with selected handle
+    // Convert pubkey to npub format (NIP-19)
+    let npub: string;
+    try {
+      npub = nip19.npubEncode(suggestion.pubkey);
+    } catch (error) {
+      console.error('Error encoding pubkey to npub:', error);
+      // Fallback to @handle if encoding fails
+      npub = suggestion.pubkey;
+    }
+    
+    // Insert as nostr:npub... format instead of @handle
+    const mentionText = `nostr:${npub} `;
+    
+    // Replace @mention with nostr:npub format
     const text = textarea.value;
     const cursorPos = textarea.selectionStart || 0;
     const textBefore = text.substring(0, mentionStart);
@@ -186,6 +205,7 @@
               src={suggestion.picture}
               alt=""
               class="avatar"
+              style="width: 1.25rem; height: 1.25rem; min-width: 1.25rem; min-height: 1.25rem; max-width: 1.25rem; max-height: 1.25rem; aspect-ratio: 1 / 1; border-radius: 50%; object-fit: cover; flex-shrink: 0; display: block;"
               onerror={(e) => {
                 (e.target as HTMLImageElement).style.display = 'none';
               }}
@@ -197,7 +217,9 @@
             <div class="suggestion-name">
               {suggestion.name || suggestion.handle || suggestion.pubkey.slice(0, 8)}
             </div>
-            {#if suggestion.handle && suggestion.name}
+            {#if suggestion.nip05}
+              <div class="suggestion-handle">{suggestion.nip05}</div>
+            {:else if suggestion.handle}
               <div class="suggestion-handle">@{suggestion.handle}</div>
             {/if}
           </div>
@@ -253,13 +275,29 @@
     background: var(--fog-dark-highlight, #374151);
   }
 
-  .avatar,
-  .avatar-placeholder {
-    width: 2rem;
-    height: 2rem;
-    border-radius: 50%;
-    flex-shrink: 0;
-    object-fit: cover;
+  .suggestion-item .avatar,
+  .suggestion-item .avatar-placeholder {
+    width: 1.25rem !important;
+    height: 1.25rem !important;
+    min-width: 1.25rem !important;
+    min-height: 1.25rem !important;
+    max-width: 1.25rem !important;
+    max-height: 1.25rem !important;
+    aspect-ratio: 1 / 1 !important;
+    border-radius: 50% !important;
+    flex-shrink: 0 !important;
+    flex-grow: 0 !important;
+    display: block !important;
+    box-sizing: border-box !important;
+  }
+  
+  .suggestion-item .avatar {
+    object-fit: cover !important;
+    image-rendering: auto;
+  }
+  
+  .suggestion-item .avatar-placeholder {
+    background: var(--fog-border, #e5e7eb);
   }
 
   .avatar-placeholder {
diff --git a/src/lib/components/layout/ProfileBadge.svelte b/src/lib/components/layout/ProfileBadge.svelte
index 5d4e945..87b52a9 100644
--- a/src/lib/components/layout/ProfileBadge.svelte
+++ b/src/lib/components/layout/ProfileBadge.svelte
@@ -143,7 +143,7 @@
       <img 
         src={profile.picture} 
         alt={profile.name || pubkey} 
-        class="profile-picture w-6 h-6 rounded flex-shrink-0"
+        class="profile-picture w-6 h-6 rounded-full flex-shrink-0"
         class:nav-picture={pictureOnly}
         loading="lazy"
         onerror={() => {
@@ -152,7 +152,7 @@
       />
     {:else}
       <div 
-        class="profile-placeholder w-6 h-6 rounded flex-shrink-0 flex items-center justify-center text-xs font-semibold"
+        class="profile-placeholder w-6 h-6 rounded-full flex-shrink-0 flex items-center justify-center text-xs font-semibold"
         class:nav-picture={pictureOnly}
         style="background: {avatarColor}; color: white;"
         title={profile?.name || pubkey}
@@ -202,18 +202,36 @@
   }
   
   .nav-picture {
-    width: 2rem;
-    height: 2rem;
+    width: 2rem !important;
+    height: 2rem !important;
+    max-width: 2rem !important;
+    max-height: 2rem !important;
+    min-width: 2rem !important;
+    min-height: 2rem !important;
   }
 
   .profile-picture {
     object-fit: cover;
     display: block;
+    aspect-ratio: 1 / 1;
+    width: 1.5rem;
+    height: 1.5rem;
+    max-width: 1.5rem;
+    max-height: 1.5rem;
+    min-width: 1.5rem;
+    min-height: 1.5rem;
   }
 
   .profile-placeholder {
     user-select: none;
     line-height: 1;
+    aspect-ratio: 1 / 1;
+    width: 1.5rem;
+    height: 1.5rem;
+    max-width: 1.5rem;
+    max-height: 1.5rem;
+    min-width: 1.5rem;
+    min-height: 1.5rem;
   }
 
   .nip05-text {
diff --git a/src/lib/services/profile-search.ts b/src/lib/services/profile-search.ts
index a931865..dd1cc44 100644
--- a/src/lib/services/profile-search.ts
+++ b/src/lib/services/profile-search.ts
@@ -16,7 +16,8 @@ import type { NostrEvent } from '../types/nostr.js';
 export interface ProfileSearchResult {
   pubkey: string;
   name?: string;
-  handle?: string; // nip05 handle
+  handle?: string; // nip05 handle (part before @)
+  nip05?: string; // full NIP-05 address
   picture?: string;
 }
 
@@ -78,6 +79,7 @@ export async function searchProfiles(
           pubkey: cursor.key as string,
           name: profile.name,
           handle: handle || undefined,
+          nip05: firstNip05 || undefined,
           picture: profile.picture
         });
       }
@@ -141,6 +143,7 @@ export async function getProfileByPubkey(
         pubkey,
         name: profile.name,
         handle: handle || undefined,
+        nip05: nip05 || undefined,
         picture: profile.picture
       };
     }
@@ -168,6 +171,7 @@ export async function getProfileByPubkey(
             pubkey,
             name: profile.name,
             handle: handle || undefined,
+            nip05: nip05 || undefined,
             picture: profile.picture
           };
         }