Remove old css and js

app/assets/stylesheets/_placeholders.scss

@@ -0,0 +1,27 @@
+@import "colors";
+@import "constants";
+
+%horizontal-list {
+  list-style-type: none;
+  margin: 0;
+  padding: 0;
+  font-size: 0px;
+  display: flex;
+  flex-wrap: wrap;
+}
+
+%horizontal-list-item {
+  display: inline-block;
+}
+
+%animation {
+  animation-fill-mode: forwards;
+  animation-duration: 0.3s;
+}
+
+%outline {
+  &:active:not(:disabled),
+  &:focus {
+    outline: 3px solid $blue;
+  }
+}