FireShot works for any webpage, but with some exceptions, which are regulated by the browser's security policy.
Fortunately, only a few page types are protected from script execution: blank, extension, and startup pages.
You can try out any other web page, for example this page.
FireShot needs your approval to capture this resource. Please go to the options and check the Allow access for file URLs box.
HINT: see this short manual how to enable this option.
And:
Stop Capturing
_Capture entire page
_Capture visible part
_Capture selection
_Capture browser window and
_Capture all tabs and
_Batch mode...
Test
_Switch to Pro!
Advanced functions ...
_Save as single PDF
_Preview
_Edit
_Save
_Save
_Save as PDF
_Print
_Copy to Clipboard
_E-Mail
_Upload
Send to One_Note
_Open in External Editor
_Options ...
To capture the full page, try FireShot with Mozilla Firefox, Microsoft Edge, Safari, or another browser.