One of the advantages of Spectra is its many customization features. This includes adding custom CSS to each individual page by selecting the Spectra Page Settings icon. You can add your own CSS code here to customize the page as per your expectations.
This opens the Spectra Page settings screen and shows a field called Custom CSS. Paste your CSS here and click Update. This allows you to customize just a single page. You have to use the selector when using this field so it knows what to apply the CSS to. This CSS field does not include line numbers and formatting.
Note:
When targeting your specific element, add
selector before the tags and classes you want to exclusively target, i.e: selector a { color: red;}