added overlay for small-box & info-box

 - moved overlay code to _miscellaneous to save lines & centralize it since its not only for card
 - changed code to flex center instead of position absolute
 - changed icon color & modified the color for dark
 - removed icon font size to use fa-lg, fa-2x, ...
 - updated widgets demo

build/scss/_cards.scss

@@ -78,41 +78,6 @@ html.maximized-card {
   overflow: hidden;
 }
 
-.card,
-.overlay-wrapper {
-  // Box overlay for LOADING STATE effect
-  > .overlay,
-  > .loading-img {
-    position: absolute;
-    top: 0;
-    left: 0;
-    width: 100%;
-    height: 100%;
-  }
-
-  .overlay {
-    z-index: 50;
-    background: rgba(255, 255, 255, 0.7);
-    @include border-radius($border-radius);
-    > .fa, 
-    > .fas,
-    > .far,
-    > .fab {
-      position: absolute;
-      top: 50%;
-      left: 50%;
-      margin-left: -15px;
-      margin-top: -15px;
-      color: #000;
-      font-size: 30px;
-    }
-  }
-
-  .overlay.dark {
-    background: rgba(0, 0, 0, 0.5);
-  }
-}
-
 // Add clearfix to header, body and footer
 .card-header,
 .card-body,

build/scss/_miscellaneous.scss

@@ -416,3 +416,45 @@ a.text-muted:hover {
   flex: 1;
 }
 
+
+// Overlays for Card, InfoBox & SmallBox
+.card,
+.overlay-wrapper,
+.info-box,
+.small-box {
+  // Box overlay for LOADING STATE effect
+  > .overlay,
+  > .loading-img {
+    position: absolute;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+  }
+
+  .overlay {
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    z-index: 50;
+    background: rgba(255, 255, 255, 0.7);
+    @include border-radius($border-radius);
+    > .fa, 
+    > .fas,
+    > .far,
+    > .fab {
+      color: $gray-800;
+    }
+
+    &.dark {
+      background: rgba(0, 0, 0, 0.5);
+      > .fa, 
+      > .fas,
+      > .far,
+      > .fab {
+        color: $gray-400;
+      }
+    }
+  }
+}
+

dist/css/adminlte.css

@@ -12736,46 +12736,6 @@ html.maximized-card {
   overflow: hidden;
 }
 
-.card > .overlay,
-.card > .loading-img,
-.overlay-wrapper > .overlay,
-.overlay-wrapper > .loading-img {
-  position: absolute;
-  top: 0;
-  left: 0;
-  width: 100%;
-  height: 100%;
-}
-
-.card .overlay,
-.overlay-wrapper .overlay {
-  z-index: 50;
-  background: rgba(255, 255, 255, 0.7);
-  border-radius: 0.25rem;
-}
-
-.card .overlay > .fa,
-.card .overlay > .fas,
-.card .overlay > .far,
-.card .overlay > .fab,
-.overlay-wrapper .overlay > .fa,
-.overlay-wrapper .overlay > .fas,
-.overlay-wrapper .overlay > .far,
-.overlay-wrapper .overlay > .fab {
-  position: absolute;
-  top: 50%;
-  left: 50%;
-  margin-left: -15px;
-  margin-top: -15px;
-  color: #000;
-  font-size: 30px;
-}
-
-.card .overlay.dark,
-.overlay-wrapper .overlay.dark {
-  background: rgba(0, 0, 0, 0.5);
-}
-
 .card-header::after,
 .card-body::after,
 .card-footer::after {
@@ -16684,6 +16644,78 @@ a.text-muted:hover {
   flex: 1;
 }
 
+.card > .overlay,
+.card > .loading-img,
+.overlay-wrapper > .overlay,
+.overlay-wrapper > .loading-img,
+.info-box > .overlay,
+.info-box > .loading-img,
+.small-box > .overlay,
+.small-box > .loading-img {
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+}
+
+.card .overlay,
+.overlay-wrapper .overlay,
+.info-box .overlay,
+.small-box .overlay {
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  z-index: 50;
+  background: rgba(255, 255, 255, 0.7);
+  border-radius: 0.25rem;
+}
+
+.card .overlay > .fa,
+.card .overlay > .fas,
+.card .overlay > .far,
+.card .overlay > .fab,
+.overlay-wrapper .overlay > .fa,
+.overlay-wrapper .overlay > .fas,
+.overlay-wrapper .overlay > .far,
+.overlay-wrapper .overlay > .fab,
+.info-box .overlay > .fa,
+.info-box .overlay > .fas,
+.info-box .overlay > .far,
+.info-box .overlay > .fab,
+.small-box .overlay > .fa,
+.small-box .overlay > .fas,
+.small-box .overlay > .far,
+.small-box .overlay > .fab {
+  color: #343a40;
+}
+
+.card .overlay.dark,
+.overlay-wrapper .overlay.dark,
+.info-box .overlay.dark,
+.small-box .overlay.dark {
+  background: rgba(0, 0, 0, 0.5);
+}
+
+.card .overlay.dark > .fa,
+.card .overlay.dark > .fas,
+.card .overlay.dark > .far,
+.card .overlay.dark > .fab,
+.overlay-wrapper .overlay.dark > .fa,
+.overlay-wrapper .overlay.dark > .fas,
+.overlay-wrapper .overlay.dark > .far,
+.overlay-wrapper .overlay.dark > .fab,
+.info-box .overlay.dark > .fa,
+.info-box .overlay.dark > .fas,
+.info-box .overlay.dark > .far,
+.info-box .overlay.dark > .fab,
+.small-box .overlay.dark > .fa,
+.small-box .overlay.dark > .fas,
+.small-box .overlay.dark > .far,
+.small-box .overlay.dark > .fab {
+  color: #ced4da;
+}
+
 /*
  * Misc: print
  * -----------

pages/widgets.html

@@ -857,6 +857,55 @@
         </div>
         <!-- /.row -->
 
+        <!-- Small Box (Stat card) -->
+        <div class="row">
+          <div class="col-lg-3 col-6">
+            <!-- small card -->
+            <div class="small-box bg-info">
+              <!-- Loading (remove the following to stop the loading)-->
+              <div class="overlay">
+                <i class="fas fa-3x fa-sync-alt"></i>
+              </div>
+              <!-- end loading -->
+              <div class="inner">
+                <h3>150</h3>
+
+                <p>New Orders</p>
+              </div>
+              <div class="icon">
+                <i class="fas fa-shopping-cart"></i>
+              </div>
+              <a href="#" class="small-box-footer">
+                More info <i class="fas fa-arrow-circle-right"></i>
+              </a>
+            </div>
+          </div>
+          <!-- ./col -->
+          <div class="col-lg-3 col-6">
+            <!-- small card -->
+            <div class="small-box bg-success">
+              <!-- Loading (remove the following to stop the loading)-->
+              <div class="overlay dark">
+                <i class="fas fa-3x fa-sync-alt"></i>
+              </div>
+              <!-- end loading -->
+              <div class="inner">
+                <h3>53<sup style="font-size: 20px">%</sup></h3>
+
+                <p>Bounce Rate</p>
+              </div>
+              <div class="icon">
+                <i class="ion ion-stats-bars"></i>
+              </div>
+              <a href="#" class="small-box-footer">
+                More info <i class="fas fa-arrow-circle-right"></i>
+              </a>
+            </div>
+          </div>
+          <!-- ./col -->
+        </div>
+        <!-- /.row -->
+
         <!-- =========================================================== -->
         <h4 class="mb-2 mt-4">Cards</h4>
         <h5 class="mb-2">Abilities</h5>
@@ -951,10 +1000,9 @@
                 <h3 class="card-title">All together</h3>
 
                 <div class="card-tools">
-                  <button type="button" class="btn btn-tool" data-widget="maximize"><i class="fas fa-expand"></i>
-                  <button type="button" class="btn btn-tool" data-widget="collapse"><i class="fas fa-minus"></i>
-                  <button type="button" class="btn btn-tool" data-widget="remove"><i class="fas fa-times"></i>
-                  </button>
+                  <button type="button" class="btn btn-tool" data-widget="maximize"><i class="fas fa-expand"></i></button>
+                  <button type="button" class="btn btn-tool" data-widget="collapse"><i class="fas fa-minus"></i></button>
+                  <button type="button" class="btn btn-tool" data-widget="remove"><i class="fas fa-times"></i></button>
                 </div>
                 <!-- /.card-tools -->
               </div>
@@ -978,7 +1026,25 @@
               <!-- /.card-body -->
               <!-- Loading (remove the following to stop the loading)-->
               <div class="overlay">
-                <i class="fas fa-sync-alt"></i>
+                <i class="fas fa-2x fa-sync-alt"></i>
+              </div>
+              <!-- end loading -->
+            </div>
+            <!-- /.card -->
+          </div>
+          <!-- /.col -->
+          <div class="col-md-3">
+            <div class="card card-warning">
+              <div class="card-header">
+                <h3 class="card-title">Loading state (dark)</h3>
+              </div>
+              <div class="card-body">
+                The body of the card
+              </div>
+              <!-- /.card-body -->
+              <!-- Loading (remove the following to stop the loading)-->
+              <div class="overlay dark">
+                <i class="fas fa-2x fa-sync-alt"></i>
               </div>
               <!-- end loading -->
             </div>