That is typical for "unformatted" webpages with various elements, styled content etc, since... decades? Looks the same with Firefox as well.
Like Ayespy said, you can take a full page capture in .png format then in a terminalconvert x.png x.pdf😉
Apologies if necroposting is against forum rules, this post comes up first when searching for this issue with few other relevant posts, and I'm not an active member.
As noted above by @Pesala, the option to change this behavior by changing keyboard shortcut settings is not present in current versions of Vivaldi on Windows - at the time of writing this, 3.5.2115.73.
I've fixed this on Windows 10 with a workaround using Chrome registry policies and now Ctrl+P (or your custom print keyboard shortcut) goes directly to the System Print Dialog.
Create a new key named Vivaldi in Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Add a new REG_DWORD in the newly created key (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Vivaldi) with the name DisablePrintPreview and a value of 1 (for true)
To confirm that the policy has been set navigate to vivaldi://policy. You may need to click Reload Policies even after restarting your browser.
If it's been set correctly DisablePrintPreview will show up with the set value, and using the Ctrl+P shortcut will go directly to the Windows System print dialog
The DisablePrintPreview policy is described on the Chrome Enterprise Policy List. As far as I know Vivaldi does not officially support Chrome policies so tread lightly and pay attention to updates.
@Pesala thanks for your help, problem solved.
hope this is the default option be checked. 🙂
or implement same as chrome,
when something selected, print selected
when nothing selected, print whole page.