chore: import upstream snapshot with attribution

docs/md/perspective.css

@@ -0,0 +1,15 @@
+perspective-viewer {
+    height: 500px;
+}
+
+div.javascript:before {
+    content: "JavaScript:";
+}
+
+div.python:before {
+    content: "Python:";
+}
+
+div.rust:before {
+    content: "Rust:";
+}