Rename app/ --> src/

src/styles/variables.scss

@@ -0,0 +1,10 @@
+// Language codes that uses CJK fonts
+/* stylelint-disable-next-line value-keyword-case -- locale filenames */
+$cjk-langs: ja, ko, zh-CN, zh-HK, zh-TW;
+
+// CSS variables
+// NOTE: Prefer CSS variables whenever possible.
+// They're future-proof and more flexible.
+:root {
+  --thumb-navigation-height: calc(60px + env(safe-area-inset-bottom));
+}