Standardize SCSS to use variables.scss and px units

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Co-Authored-By: Claude <noreply@anthropic.com>

app/RSpade/Core/Js/Responsive.js

@@ -27,7 +27,7 @@ class Responsive {
         }
 
         const styles = getComputedStyle(document.documentElement);
-        const value = styles.getPropertyValue(`--bp-${name}-min`).trim();
+        const value = styles.getPropertyValue(`--${name}`).trim();
         const parsed = parseInt(value, 10);
 
         this._cache[name] = parsed;