Whether CSS class selectors are case sensitive by default depends on the doctype. This can be overridden by using the caseSensitiveClassSelectors QuirksSettings property.
Java
config.setQuirksSettings(new QuirksSettings().setCaseSensitiveClassSelectors(QuirksMode.STANDARDS));
C#
config.QuirksSettings = new QuirksSettings { CaseSensitiveClassSelectors = QuirksMode.STANDARDS };
PHP
$config["quirksSettings"] = array( "caseSensitiveClassSelectors" => QuirksMode::STANDARDS );
JavaScript/Node.js
config.quirksSettings = { caseSensitiveClassSelectors: PDFreactor.QuirksMode.STANDARDS };
Python
config["quirksSettings"] = { "caseSensitiveClassSelectors": PDFreactor.QuirksMode.STANDARDS }
Ruby
config["quirksSettings"] = { caseSensitiveClassSelectors: PDFreactor::QuirksMode::STANDARDS }
Perl
$config["quirksSettings"] = { "caseSensitiveClassSelectors" => PDFreactor::QuirksMode->STANDARDS };
REST
{ "quirksSettings"]: { "caseSensitiveClassSelectors": "STANDARDS" }}