Move theme alterations to global CSS file

assets/global.css

@@ -1,3 +1,9 @@
+/* change them */
+:root {
+    --mdc-theme-primary: #00adb4;
+    --mdc-theme-secondary: #d84315;
+}
+
 /* implement colour theme on elements that don't have it applied by default */
 .mdc-text-field--focused:not(.mdc-text-field--disabled) .mdc-floating-label, .mdc-list-item--activated .mdc-list-item__text, .mdc-drawer .mdc-list-item--activated .mdc-list-item__graphic {
    color: var(--mdc-theme-primary);

luhn-algorithm/index.html

@@ -41,7 +41,6 @@
         <!-- import local styling & scripts -->
         <script src="script.js"></script>
         <script src="/assets/global.js"></script>
-        <link href="style.css" rel="stylesheet">
         <link href="/assets/global.css" rel="stylesheet">
 
         <!-- Global site tag (gtag.js) - Google Analytics -->

luhn-algorithm/style.css

@@ -1,7 +0,0 @@
-:root {
-    --mdc-theme-primary: #00adb4;
-    --mdc-theme-secondary: #d84315;
-}
-.mdc-text-field-helper-text {
-    margin-bottom: 10px;
-}