Selam :) Admin Paneli > Theme Options > Styling Option > Custom Css kısmına aşağıdaki kodu ekleyin. Kolay gelsin.

#author,#email,#url{max-width: 100%!important;background:rgba(0, 0, 0,0.035)!important;height:48px!important;font-size:16px}#commentform textarea{background:rgba(0, 0, 0, 0.035)!important;font-size:16px}input.submit{font-size: 16px;padding: 13px 40px 13px 40px !important;}