With zeroheight, you have options for securing your styleguides.

Password protection can be enabled at the styleguide level or on individual pages. When accessing a password-protected styleguide, viewers are taken to a login screen (which you can customize). If you choose to password-protect individual pages instead, users will be prompted to enter the password when navigating to the secured page.

You can also change the password at any time for even more control over styleguide security.