diff --git a/frontend/src/pages/auth/sign-in.astro b/frontend/src/pages/auth/sign-in.astro
index ae4549f..48ac856 100644
--- a/frontend/src/pages/auth/sign-in.astro
+++ b/frontend/src/pages/auth/sign-in.astro
@@ -307,6 +307,46 @@ import { SITE_URL } from '@constants';
         transform: translateY(0);
     }
 
+    .btn-submit:disabled {
+        background: #94a3b8;
+        cursor: not-allowed;
+        transform: none;
+        box-shadow: none;
+    }
+
+    .btn-submit:disabled:hover {
+        transform: none;
+        box-shadow: none;
+    }
+
+    .btn-submit.loading,
+    .btn-submit.loading:disabled {
+        position: relative;
+        color: transparent !important;
+        pointer-events: none;
+        opacity: 1 !important;
+        background: linear-gradient(135deg, #eac26e 0%, #ce9f40 100%) !important;
+    }
+
+    .btn-submit.loading::after {
+        content: '';
+        position: absolute;
+        width: 20px;
+        height: 20px;
+        top: 50%;
+        left: 50%;
+        margin-left: -10px;
+        margin-top: -10px;
+        border: 2px solid #ffffff;
+        border-radius: 50%;
+        border-top-color: transparent;
+        animation: spin 0.8s linear infinite;
+    }
+
+    @keyframes spin {
+        to { transform: rotate(360deg); }
+    }
+
     /* Подвал формы */
     .auth-footer {
         text-align: center;
@@ -554,7 +594,7 @@ import { SITE_URL } from '@constants';
 
         const submitBtn = document.querySelector('.btn-submit') as HTMLButtonElement;
         submitBtn.disabled = true;
-        submitBtn.textContent = 'Вход...';
+        submitBtn.classList.add('loading');
 
         try {
             const response = await fetch('/api/auth/sign-in', {