diff --git a/index/css/style.css b/index/css/style.css
index 4594be8..76bd808 100644
--- a/index/css/style.css
+++ b/index/css/style.css
@@ -16,18 +16,6 @@ body {
 .custom-control-label:hover {
     cursor: pointer;
 }
-.loading-overlay {
-    position: absolute;
-    top:0;
-    display: grid;
-    width: 100%;
-    height: 100%;
-    background-color: rgba(0,0,0,.5);
-    z-index: 99;
-}
-.loading-overlay div {
-    margin:auto;
-}
 #choose-service, #choose-function, #body-request {
     margin-top: 40px;
 }
@@ -64,3 +52,57 @@ body {
         animation:octocat-wave 560ms ease-in-out
     }
 }
+
+/* loading spinner */
+.spinner {
+    margin: 10px auto;
+    width: 180px;
+    height: 80px;
+    text-align: center;
+    font-size: 80px;
+}
+
+.spinner > div {
+    background-color: #59698d;
+    height: 100%;
+    width: 18px;
+    display: inline-block;
+
+    -webkit-animation: sk-stretchdelay 1.2s infinite ease-in-out;
+    animation: sk-stretchdelay 1.2s infinite ease-in-out;
+}
+
+.spinner .rect2 {
+    -webkit-animation-delay: -1.1s;
+    animation-delay: -1.1s;
+}
+
+.spinner .rect3 {
+    -webkit-animation-delay: -1.0s;
+    animation-delay: -1.0s;
+}
+
+.spinner .rect4 {
+    -webkit-animation-delay: -0.9s;
+    animation-delay: -0.9s;
+}
+
+.spinner .rect5 {
+    -webkit-animation-delay: -0.8s;
+    animation-delay: -0.8s;
+}
+
+@-webkit-keyframes sk-stretchdelay {
+    0%, 40%, 100% { -webkit-transform: scaleY(0.4) }
+    20% { -webkit-transform: scaleY(1.0) }
+}
+
+@keyframes sk-stretchdelay {
+    0%, 40%, 100% {
+        transform: scaleY(0.4);
+        -webkit-transform: scaleY(0.4);
+    }  20% {
+        transform: scaleY(1.0);
+        -webkit-transform: scaleY(1.0);
+    }
+}
\ No newline at end of file
diff --git a/index/index.html b/index/index.html
index 9606dcd..b0d07b5 100644
--- a/index/index.html
+++ b/index/index.html
@@ -92,25 +92,12 @@
     </svg>
   </a>
 
-  <div class="loading-overlay" style="display: none">
-    <div><svg width="200px" height="200px" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="xMidYMid"
-        class="lds-flat-ball" style="background: none;">
-        <defs>
-          <mask ng-attr-id="{{config.mid}}" id="lds-flat-ball-mask-e49120e4825">
-            <circle cx="50" cy="50" r="45" fill="#fff"></circle>
-          </mask>
-        </defs>
-        <circle cx="50" cy="50" r="45" ng-attr-fill="{{config.base}}" fill="#85a2b6"></circle>
-        <path ng-attr-fill="{{config.dark}}" mask="url(#lds-flat-ball-mask-e49120e4825)" fill="rgb(107, 131, 147)" d="M 37.2721 55.3778 L 62.7279 29.922 L 162.728 129.922 L 137.272 155.378 Z">
-          <animate attributeName="d" calcMode="spline" values="M 37.27207793864214 40.72792206135786 L 62.72792206135786 15.272077938642143 L 162.72792206135784 115.27207793864214 L 137.27207793864216 140.72792206135784 Z;M 37.27207793864214 84.72792206135786 L 62.72792206135786 59.27207793864214 L 162.72792206135784 159.27207793864216 L 137.27207793864216 184.72792206135784 Z;M 37.27207793864214 40.72792206135786 L 62.72792206135786 15.272077938642143 L 162.72792206135784 115.27207793864214 L 137.27207793864216 140.72792206135784 Z"
-            keyTimes="0;0.5;1" dur="1" keySplines="0.45 0 0.9 0.55;0 0.45 0.55 0.9" begin="0s" repeatCount="indefinite"></animate>
-        </path>
-        <circle cx="50" ng-attr-cy="{{config.cy}}" ng-attr-r="{{config.radius}}" ng-attr-fill="{{config.color}}" cy="42.6499"
-          r="18" fill="#fdfdfd">
-          <animate attributeName="cy" calcMode="spline" values="28;72;28" keyTimes="0;0.5;1" dur="1" keySplines="0.45 0 0.9 0.55;0 0.45 0.55 0.9"
-            begin="0s" repeatCount="indefinite"></animate>
-        </circle>
-      </svg></div>
+  <div class="spinner" style="display: none">
+    <div class="rect1"></div>
+    <div class="rect2"></div>
+    <div class="rect3"></div>
+    <div class="rect4"></div>
+    <div class="rect5"></div>
   </div>
 
   <script type="text/javascript" src="js/jquery-3.3.1.min.js"></script>
diff --git a/index/js/style.js b/index/js/style.js
index e2757a0..b299d95 100644
--- a/index/js/style.js
+++ b/index/js/style.js
@@ -32,11 +32,14 @@ $('#get-services').click(function(){
             alert(errorThrown);
         },
         beforeSend: function(xhr){
+            $('#choose-service').hide();
             xhr.setRequestHeader('use_tls', use_tls);
             $(this).html("Loading...");
+            show_loading();
         },
         complete: function(){
             $(this).html(button);
+            hide_loading();
         }
     });
 });
@@ -64,6 +67,7 @@ $('#select-service').change(function(){
         },
         error: err,
         beforeSend: function(xhr){
+            $('#choose-function').hide();
             xhr.setRequestHeader('use_tls', use_tls);
             show_loading();
         },
@@ -96,6 +100,7 @@ $('#select-function').change(function(){
         },
         error: err,
         beforeSend: function(xhr){
+            $('#body-request').hide();
             xhr.setRequestHeader('use_tls', use_tls);
             show_loading();
         },
@@ -129,11 +134,14 @@ $('#invoke-func').click(function(){
         },
         error: err,
         beforeSend: function(xhr){
+            $('#response').hide();
             xhr.setRequestHeader('use_tls', use_tls);
             $(this).html("Loading...");
+            show_loading();
         },
         complete: function(){
             $(this).html(button);
+            hide_loading();
         }
     });
 });
@@ -173,9 +181,9 @@ function err(_, _, errorThrown) {
 }
 
 function show_loading() {
-    $('.loading-overlay').show();
+    $('.spinner').show();
 }
 
 function hide_loading() {
-    $('.loading-overlay').hide();
+    $('.spinner').hide();
 }
\ No newline at end of file