diff --git a/assets/css/routes/sign.css b/assets/css/routes/sign.css
index 9541ddee..d350e486 100644
--- a/assets/css/routes/sign.css
+++ b/assets/css/routes/sign.css
@@ -89,9 +89,9 @@
 #u_sign.has-sign-img .modal-dialog { width: 800px; }
 #u_sign .modal-content { position: relative; min-height: 300px; max-height: calc(100vh - 36px); overflow-x: hidden; overflow-y: auto; border: 0; border-radius: 8px; background: var(--main-bg-color, #fff); box-shadow: 0 12px 50px rgba(0, 0, 0, .22); }
 .auth-modal-close { position: absolute; top: 13px; right: 15px; z-index: 4; width: 30px; height: 30px; border: 0; border-radius: 50%; background: rgba(0, 0, 0, .04); color: var(--muted-color, #777); cursor: pointer; }
-.sign-img { position: absolute; inset: 0 55% 0 0; overflow: hidden; }
-.sign-img img { display: block; width: 100%; height: 100%; border-radius: 8px 0 0 8px; object-fit: cover; }
-.sign-img + .sign { max-width: unset; margin-left: 55%; padding: 34px 44px; }
+#u_sign .sign-img { position: absolute; inset: 0 45% 0 0; overflow: hidden; padding: 0; }
+#u_sign .sign-img img { display: block; width: 100%; height: 100%; border-radius: 8px 0 0 8px; object-fit: cover; }
+#u_sign .sign-img + .sign { max-width: unset; margin-left: 55%; padding: 34px 44px; }
 
 .page-template-user-sign { min-height: 100vh; background: var(--body-bg-color, #f5f6f7); }
 .sign-page-background { position: fixed; inset: 0; z-index: 0; background-position: center; background-size: cover; }
@@ -109,8 +109,8 @@ body.auth-modal-open { overflow: hidden; }
 @media (max-width: 767px) {
   #u_sign .modal-dialog,
   #u_sign.has-sign-img .modal-dialog { width: 400px; }
-  .sign-img { display: none; }
-  .sign-img + .sign { max-width: 340px; margin-left: auto; padding: 30px 0; }
+  #u_sign .sign-img { display: none; }
+  #u_sign .sign-img + .sign { max-width: 340px; margin-left: auto; padding: 30px 0; }
   #u_sign .modal-content { padding: 0 24px; }
   .sign-page { justify-content: center !important; padding-right: 14px; padding-left: 14px; }
   .sign-page-card { padding: 0 24px; }
diff --git a/tests/widget-system/auth-source-contract.test.cjs b/tests/widget-system/auth-source-contract.test.cjs
index 1b96e77a..b8a09e7c 100644
--- a/tests/widget-system/auth-source-contract.test.cjs
+++ b/tests/widget-system/auth-source-contract.test.cjs
@@ -31,6 +31,8 @@ test('static Zibll authentication dimensions and responsive contract are retaine
   const css = read('assets/css/routes/sign.css');
   assert.match(css, /\.sign\s*\{[\s\S]*?max-width:\s*330px/);
   assert.match(css, /#u_sign\.has-sign-img \.modal-dialog\s*\{\s*width:\s*800px/);
+  assert.match(css, /#u_sign \.sign-img\s*\{[^}]*inset:\s*0 45% 0 0;[^}]*padding:\s*0/);
+  assert.match(css, /#u_sign \.sign-img \+ \.sign\s*\{[^}]*margin-left:\s*55%/);
   assert.match(css, /\.social-login-item\s*\{[\s\S]*?width:\s*32px;[\s\S]*?height:\s*32px/);
   assert.match(css, /\.auth-qrcode\s*\{[\s\S]*?width:\s*180px;[\s\S]*?min-height:\s*180px/);
   assert.match(css, /@media \(max-width:\s*767px\)[\s\S]*?\.sign-img\s*\{\s*display:\s*none/);