Test check (iii) and fix two bugs it exposed in the application-CSS scan

Plan step 41(iii): fixtures/tests for every literal kind (colour, radius,
shadow, font size/weight, line height, letter spacing, easing, duration) and
an off-scale media query, plus material-scheme.css excluded by name and by
its generated header wherever it sits among the scanned paths. Also adds a
fixture proving Tailwind-shaped bare words in running prose are never read
as classes.

Two fixes found by writing the fixtures rather than only the implementation:
a directly-scanned .css file was also running through the Blade/PHP/JS checks
(the same file's `ease-in-out` in a `transition` value tripped the old scale
check a second time), so a CSS file is now check (iii)'s alone; and
`withoutTokenFunctions()` leaves a `var()`/`calc()` call's own name and
parentheses standing once its arguments are blanked, which
`isSafeLiteralValue()` did not yet recognise as the same "nothing to see
here" as an empty value.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

src/Testing/DesignGuard.php

@@ -325,6 +325,10 @@ class DesignGuard
         }
 
         foreach ($this->files() as $file) {
+            if (str_ends_with($file->getFilename(), '.css')) {
+                continue; // A directly-scanned CSS file is check (iii)'s alone; these checks read Blade, PHP and JS.
+            }
+
             $contents = (string) file_get_contents($file->getPathname());
             $where = $this->relative($file->getPathname());
             $isBlade = str_ends_with($file->getFilename(), '.blade.php');
@@ -671,7 +675,7 @@ class DesignGuard
      */
     protected function literalColours(string $css): array
     {
-        $pattern = '/(?<![\w#-])(?:#[0-9a-fA-F]{3,8}\b|(?:rgb|rgba|hsl|hsla|oklch|oklab|lch|lab|color)\(|(?<=[:,(]\s{0,20})(?:'.self::CSS_NAMED_COLOURS.')\b(?!-))/i';
+        $pattern = '/(?<![\w#-])(?:#[0-9a-fA-F]{3,8}\b|(?:rgb|rgba|hsl|hsla|oklch|oklab|lch|lab|color)\([^)]*\)|(?<=[:,(]\s{0,20})(?:'.self::CSS_NAMED_COLOURS.')\b(?!-))/i';
 
         preg_match_all($pattern, $css, $matches, PREG_OFFSET_CAPTURE);
 
@@ -731,9 +735,16 @@ class DesignGuard
         return $found;
     }
 
+    /**
+     * A value `withoutTokenFunctions()` left with nothing but the empty shell of a `var()`/`calc()`
+     * call — whitespace where the call's own argument list used to be, the call's own name and
+     * parentheses still standing — is exactly as fine as one masked away entirely.
+     */
     protected function isSafeLiteralValue(string $value): bool
     {
-        return trim($value) === '' || in_array(strtolower(trim($value)), ['0', '0px', '0s', 'none', 'inherit', 'initial', 'unset', 'normal', 'auto'], true);
+        $value = trim((string) preg_replace('/\b(?:var|calc)\(\s*\)/i', '', $value));
+
+        return $value === '' || in_array(strtolower($value), ['0', '0px', '0s', 'none', 'inherit', 'initial', 'unset', 'normal', 'auto'], true);
     }
 
     /**