feat: add common animation.scss

Author: wewoor

src/style/animation.scss

@@ -0,0 +1,13 @@
+@keyframes fadeIn {
+    0% {
+        opacity: 0;
+    }
+    
+    100% {
+        opacity: 1;
+    }
+}
+
+.fade-in {
+    animation: fadeIn 0.083s linear;
+}