move frontend stuff to its own directory

frontend/src/main.css

@@ -0,0 +1,17 @@
+@import "bulma/css/bulma.css";
+
+:root {
+  --bulma-primary-h: 220deg;
+  --bulma-primary-s: 60%;
+  --bulma-primary-l: 50%;
+}
+
+.navbar {
+  --bulma-navbar-burger-color: var(--bulma-white);
+  --bulma-navbar-dropdown-border-color: var(--bulma-primary);
+}
+
+.overflow-y {
+  overflow-y: auto;
+  max-height: 30vh;
+}