As for CSS, suppose the easiest way is to look for <link rel="stylesheet" type="text/css" (...) /> line and extract CSS filename with preg_match(). Then, use cURL in next iteration to fetch CSS file...
Now, colors can come in many flavors. Are you seeking for text colors, bground colors, or literally everything? Bottom line, you have to use series of preg_match() to find all HTML / CSS variations and extract colors...
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