minor restyling of login screen (#2711)

assets/sass/app.scss

@@ -30,3 +30,4 @@
 @import 'modal';
 @import 'progressbar';
 @import 'avatar';
+@import 'security';

assets/sass/security.scss

@@ -0,0 +1,35 @@
+body.login-page {
+    .alert {
+        margin-bottom: 0;
+    }
+    .login-box-body {
+        text-align: center;
+        padding: 30px 35px;
+        box-shadow: 0 10px 30px 0 rgba(172, 168, 168, 0.43);
+        .btn {
+            padding: 7px;
+            font-size: 115%;
+        }
+    }
+    .login-head {
+        margin-top: 0;
+    }
+    .login-actions a {
+        display: block;
+    }
+    .form-group {
+        input[type=password], input[type=text] {
+            padding: 20px 15px;
+        }
+    }
+    span.glyphicon {
+        display: none;
+    }
+}
+@media (max-width: $screen-sm-max) {
+    body.login-page {
+        .login-box-body {
+            padding: 20px 27px;
+        }
+    }
+}