Customizing captcha
You can change shape and colors of the Captcha component. To set custom styles edit captcha-customize.css stylesheet.
/Scripts/default/assets/css/captcha-customize.css
This file will be included every time you call the Captcha control in your code.
<titan:Captcha runat="server" ID="TitanCaptcha1" />
If necessary, you can also make some minor changes in the HTML structure of the Captcha component Captcha.ascx
\Controls\Captcha.ascx