Add skeleton feature

src/style.less

@@ -0,0 +1,35 @@
+// This part add to "Design system" component
+@keyframes idm-skeleton-loading {
+  to {
+    background-position-x: -200%;
+  }
+}
+
+.skeleton(@width, @height, @mobileWidth, @mobileHeight, @borderRadius) {
+  position: relative;
+  overflow: hidden;
+
+  &.idm-loading {
+    transition: none;
+    border-radius: @borderRadius;
+    background: #eee;
+    background: linear-gradient(110deg, #ececec 8%, #f5f5f5 18%, #ececec 33%);
+    background-size: 200% 100%;
+    animation: 1.5s idm-skeleton-loading linear infinite;
+    width: @width;
+    height: @height;
+
+    // Mobile adaptation
+    @media (max-width: 756px) {
+      width: @mobileWidth;
+      height: @mobileHeight;
+    }
+  }
+}
+
+// Example of use
+.wrapper {
+  .element {
+   .skeleton(100%, 50vh, 300px, 100px, 3rem);
+  }
+}