update blue-to-green styling

Author: StevenClontz

index.html

@@ -9,6 +9,7 @@
 <title>code4math</title>
 <meta name="description" content="Consortium of Digital Ecosystems for Mathematics" />
 <link rel="stylesheet" href="./simple.min.css">
+<style>:root {--accent-bg: #f7fff5; --accent: #47a10d}</style>
 
 <link rel="icon" href="/favicon.png" />
 <link rel="apple-touch-icon" href="/favicon.png">