loop/webui: add prettier
diff --git a/loop/webui/src/sketch-app-shell.html b/loop/webui/src/sketch-app-shell.html
index 6a9f1c3..8d1a30c 100644
--- a/loop/webui/src/sketch-app-shell.html
+++ b/loop/webui/src/sketch-app-shell.html
@@ -1,4 +1,4 @@
-<!DOCTYPE html>
+<!doctype html>
 <html lang="en">
   <head>
     <meta charset="UTF-8" />
@@ -12,8 +12,13 @@
         overflow-y: auto;
       }
       body {
-        font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
-          Roboto, sans-serif;
+        font-family:
+          system-ui,
+          -apple-system,
+          BlinkMacSystemFont,
+          "Segoe UI",
+          Roboto,
+          sans-serif;
         margin: 0;
         padding: 0;
         color: #333;